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Red Hat Enterprise Linux 5
Cluster Administration
Configuring and Managing a Red Hat Cluster
Edition 5
Red Hat Enterprise Linux 5 Cluster Administration
Configuring and Managing a Red Hat Cluster
Edition 5
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Abstract
Co nfiguring and Managing a Red Hat Cluster describes the co nfiguratio n and management o f
Red Hat cluster systems fo r Red Hat Enterprise Linux 5. It do es no t include info rmatio n abo ut
Red Hat Linux Virtual Servers (LVS). Info rmatio n abo ut installing and co nfiguring LVS is in a separate do cument.
Table of Contents
1.1. Typ o g rap hic Co nventio ns
1.2. Pull-q uo te Co nventio ns
1.1.2. Installing Red Hat Cluster so ftware
1.1.2.1. Up g rad ing the Cluster So ftware
1.1.3. Co nfig uring Red Hat Cluster So ftware
1.3. system-co nfig -cluster Cluster Ad ministratio n G UI
1.3.1. Cluster Co nfig uratio n To o l
1.4. Co mmand Line Ad ministratio n To o ls
2.1. G eneral Co nfig uratio n Co nsid eratio ns
2.3.1. Enab ling IP Po rts o n Cluster No d es
2.3.2. Enab ling IP Po rts o n Co mp uters That Run luci
2.4. Co nfig uring ACPI Fo r Use with Integ rated Fence Devices
2.4.1. Disab ling ACPI So ft-O ff with chkco nfig Manag ement
2.4.2. Disab ling ACPI So ft-O ff with the BIO S
2.4.3. Disab ling ACPI Co mp letely in the g rub .co nf File
2.5. Co nsid eratio ns fo r Co nfig uring HA Services
2.7. Co nsid eratio ns fo r Using Q uo rum Disk
2.8 . Red Hat Cluster Suite and SELinux
2.10 . Co nfig uring the ip tab les Firewall to Allo w Cluster Co mp o nents
2.11. Co nsid eratio ns fo r Using Co ng a
2.12. Co nfig uring Virtual Machines in a Clustered Enviro nment
3.4. G lo b al Cluster Pro p erties
3.5. Co nfig uring Fence Devices
3.5.1. Creating a Shared Fence Device
3.5.2. Mo d ifying o r Deleting a Fence Device
3.6 . Co nfig uring Cluster Memb ers
3.6 .1. Initially Co nfig uring Memb ers
3.6 .2. Ad d ing a Memb er to a Running Cluster
3.6 .3. Deleting a Memb er fro m a Cluster
3.7. Co nfig uring a Failo ver Do main
3.7.1. Ad d ing a Failo ver Do main
3.7.2. Mo d ifying a Failo ver Do main
T able of Cont ent s
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10
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17
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8
9
4
4
6
6
7
31
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25
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30
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24
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41
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36
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39
34
34
35
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Red Hat Ent erprise Linux 5 Clust er Administ rat ion
3.7.2. Mo d ifying a Failo ver Do main
3.8 . Ad d ing Cluster Reso urces
3.9 . Ad d ing a Cluster Service to the Cluster
3.10 . Co nfig uring Cluster Sto rag e
4.1. Starting , Sto p p ing , and Deleting Clusters
4.2. Manag ing Cluster No d es
4.3. Manag ing Hig h-Availab ility Services
4.4. Backing Up and Resto ring the luci Co nfig uratio n
4.5. Diag no sing and Co rrecting Pro b lems in a Cluster
5.2. Starting the Cluster Co nfig uratio n To o l
Custo m Co nfig ure Multicast
5.3. Co nfig uring Cluster Pro p erties
5.4. Co nfig uring Fence Devices
5.5. Ad d ing and Deleting Memb ers
5.5.1. Ad d ing a Memb er to a Cluster
5.5.2. Ad d ing a Memb er to a Running Cluster
5.5.2.1. Ad d ing a Memb er to a Running Cluster That Co ntains O nly Two No d es
5.5.2.2. Ad d ing a Memb er to a Running Cluster That Co ntains Mo re Than Two No d es
5.5.3. Deleting a Memb er fro m a Cluster
5.5.3.1. Remo ving a Memb er fro m a Cluster at the Co mmand -Line
5.6 . Co nfig uring a Failo ver Do main
5.6 .1. Ad d ing a Failo ver Do main
5.6 .2. Remo ving a Failo ver Do main
5.6 .3. Remo ving a Memb er fro m a Failo ver Do main
5.7. Ad d ing Cluster Reso urces
5.8 . Ad d ing a Cluster Service to the Cluster
5.8 .1. Relo cating a Service in a Cluster
5.9 . Pro p ag ating The Co nfig uratio n File: New Cluster
5.10 . Starting the Cluster So ftware
6 .1. Starting and Sto p p ing the Cluster So ftware
6 .2. Manag ing Hig h-Availab ility Services
6 .3. Mo d ifying the Cluster Co nfig uratio n
6 .4. Backing Up and Resto ring the Cluster Datab ase
6 .5. Disab ling Reso urces o f a Clustered Service fo r Maintenance
6 .6 . Disab ling the Cluster So ftware
6 .7. Diag no sing and Co rrecting Pro b lems in a Cluster
A.1. Ap ache HTTP Server Setup O verview
A.2. Co nfig uring Shared Sto rag e
A.3. Installing and Co nfig uring the Ap ache HTTP Server
52
53
54
55
55
46
47
47
50
78
78
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8 1
8 2
8 3
8 4
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8 5
8 6
6 7
6 8
6 9
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72
6 4
6 4
6 5
6 5
6 6
56
57
58
58
6 2
6 3
72
73
73
76
76
76
110
2
D.1. Parent, Child , and Sib ling Relatio nship s Amo ng Reso urces
T able of Cont ent s
D.1. Parent, Child , and Sib ling Relatio nship s Amo ng Reso urces
D.2. Sib ling Start O rd ering and Reso urce Child O rd ering
D.2.1. Typ ed Child Reso urce Start and Sto p O rd ering
Typ ed Child Reso urce Starting O rd er
Typ ed Child Reso urce Sto p p ing O rd er
D.2.2. No n-typ ed Child Reso urce Start and Sto p O rd ering
No n-typ ed Child Reso urce Starting O rd er
No n-typ ed Child Reso urce Sto p p ing O rd er
D.3. Inheritance, the < reso urces> Blo ck, and Reusing Reso urces
D.4. Failure Reco very and Ind ep end ent Sub trees
D.5. Deb ug g ing and Testing Services and Reso urce O rd ering
E.1. Mo d ifying the Reso urce Status Check Interval
E.2. Enfo rcing Reso urce Timeo uts
E.3. Chang ing Co nsensus Timeo ut
119
119
120
F.2. Co nfig uring HA-LVM Failo ver with Tag g ing
124 123
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111
112
113
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113
114
115
115
116
117
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Red Hat Ent erprise Linux 5 Clust er Administ rat ion
Introduction
This document provides information about installing, configuring and managing Red Hat Cluster components. Red Hat Cluster components are part of Red Hat Cluster Suite and allow you to connect a group of computers (called nodes or members) to work together as a cluster. This document does not include information about installing, configuring, and managing Linux Virtual Server (LVS) software. Information about that is in a separate document.
The audience of this document should have advanced working knowledge of Red Hat Enterprise
Linux and understand the concepts of clusters, storage, and server computing.
For more information about Red Hat Enterprise Linux 5, refer to the following resources:
Red Hat Enterprise Linux Installation Guide — Provides information regarding installation of Red Hat
Enterprise Linux 5.
Red Hat Enterprise Linux Deployment Guide — Provides information regarding the deployment, configuration and administration of Red Hat Enterprise Linux 5.
For more information about Red Hat Cluster Suite for Red Hat Enterprise Linux 5, refer to the following resources:
Red Hat Cluster Suite Overview — Provides a high level overview of the Red Hat Cluster Suite.
Logical Volume Manager Administration — Provides a description of the Logical Volume Manager
(LVM), including information on running LVM in a clustered environment.
Global File System: Configuration and Administration — Provides information about installing, configuring, and maintaining Red Hat GFS (Red Hat Global File System).
Global File System 2: Configuration and Administration — Provides information about installing, configuring, and maintaining Red Hat GFS2 (Red Hat Global File System 2).
Using Device-Mapper Multipath — Provides information about using the Device-Mapper Multipath feature of Red Hat Enterprise Linux 5.
Using GNBD with Global File System — Provides an overview on using Global Network Block
Device (GNBD) with Red Hat GFS.
Linux Virtual Server Administration — Provides information on configuring high-performance systems and services with the Linux Virtual Server (LVS).
Red Hat Cluster Suite Release Notes — Provides information about the current release of Red Hat
Cluster Suite.
Red Hat Cluster Suite documentation and other Red Hat documents are available in HTML, PDF, and
RPM versions on the Red Hat Enterprise Linux Documentation CD and https://access.redhat.com/site/documentation/en-US/ .
1. Document Convent ions
This manual uses several conventions to highlight certain words and phrases and draw attention to specific pieces of information.
1.1. T ypographic Convent ions
4
Int roduct ion
Four typographic conventions are used to call attention to specific words and phrases. These conventions, and the circumstances they apply to, are as follows.
Mono-spaced Bold
Used to highlight system input, including shell commands, file names and paths. Also used to highlight keys and key combinations. For example:
To see the contents of the file my_next_bestselling_novel in your current working directory, enter the cat my_next_bestselling_novel command at the shell prompt and press Enter to execute the command.
The above includes a file name, a shell command and a key, all presented in mono-spaced bold and all distinguishable thanks to context.
Key combinations can be distinguished from an individual key by the plus sign that connects each part of a key combination. For example:
Press Enter to execute the command.
Press Ctrl+Alt+F2 to switch to a virtual terminal.
The first example highlights a particular key to press. The second example highlights a key combination: a set of three keys pressed simultaneously.
If source code is discussed, class names, methods, functions, variable names and returned values mentioned within a paragraph will be presented as above, in mono-spaced bold. For example:
File-related classes include filesystem for file systems, file for files, and dir for directories. Each class has its own associated set of permissions.
Pro p o rt io n al Bo ld
This denotes words or phrases encountered on a system, including application names; dialog-box text; labeled buttons; check-box and radio-button labels; menu titles and submenu titles. For example:
Choose Syst em → Pref eren ces → Mo u se from the main menu bar to launch
Mo u se Pref eren ces. In the Buttons tab, select the Left-handed mouse check box and click Close to switch the primary mouse button from the left to the right
(making the mouse suitable for use in the left hand).
To insert a special character into a g ed it file, choose Ap p licat io n s →
Accesso ries → Ch aract er Map from the main menu bar. Next, choose Search →
Fin d … from the Ch aract er Map menu bar, type the name of the character in the
Search field and click Next. The character you sought will be highlighted in the
Character Table. Double-click this highlighted character to place it in the Text
to copy field and then click the Copy button. Now switch back to your document and choose Ed it → Past e from the g ed it menu bar.
The above text includes application names; system-wide menu names and items; application-specific menu names; and buttons and text found within a GUI interface, all presented in proportional bold and all distinguishable by context.
Mono-spaced Bold Italic or Proportional Bold Italic
Whether mono-spaced bold or proportional bold, the addition of italics indicates replaceable or variable text. Italics denotes text you do not input literally or displayed text that changes depending on circumstance. For example:
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Red Hat Ent erprise Linux 5 Clust er Administ rat ion
To connect to a remote machine using ssh, type ssh username@domain.name at a shell prompt. If the remote machine is example.com and your username on that machine is john, type ssh [email protected].
The mount -o remount file-system command remounts the named file system.
For example, to remount the /home file system, the command is mount -o remount
/home.
To see the version of a currently installed package, use the rpm -q package command. It will return a result as follows: package-version-release.
Note the words in bold italics above: username, domain.name, file-system, package, version and release. Each word is a placeholder, either for text you enter when issuing a command or for text displayed by the system.
Aside from standard usage for presenting the title of a work, italics denotes the first use of a new and important term. For example:
Publican is a DocBook publishing system.
1.2. Pull-quot e Convent ions
Terminal output and source code listings are set off visually from the surrounding text.
Output sent to a terminal is set in mono-spaced roman and presented thus: books Desktop documentation drafts mss photos stuff svn books_tests Desktop1 downloads images notes scripts svgs
Source-code listings are also set in mono-spaced roman but add syntax highlighting as follows: static int kvm_vm_ioctl_deassign_device( struct kvm *kvm,
struct kvm_assigned_pci_dev *assigned_dev)
{
int r = 0;
struct kvm_assigned_dev_kernel *match;
mutex_lock(&kvm->lock);
match = kvm_find_assigned_dev(&kvm->arch.assigned_dev_head,
assigned_dev->assigned_dev_id);
if (!match) {
printk(KERN_INFO "%s: device hasn't been assigned before, "
"so cannot be deassigned \n " , __func__);
r = -EINVAL;
goto out;
}
kvm_deassign_device(kvm, match);
kvm_free_assigned_device(kvm, match);
out:
mutex_unlock(&kvm->lock);
return r;
}
1.3. Not es and Warnings
6
Int roduct ion
Finally, we use three visual styles to draw attention to information that might otherwise be overlooked.
Note
Notes are tips, shortcuts or alternative approaches to the task at hand. Ignoring a note should have no negative consequences, but you might miss out on a trick that makes your life easier.
Important
Important boxes detail things that are easily missed: configuration changes that only apply to the current session, or services that need restarting before an update will apply. Ignoring a box labeled “ Important” will not cause data loss but may cause irritation and frustration.
Warning
Warnings should not be ignored. Ignoring warnings will most likely cause data loss.
2. Feedback
If you spot a typo, or if you have thought of a way to make this manual better, we would love to hear from you. Please submit a report in Bugzilla ( http://bugzilla.redhat.com/bugzilla/ ). File the bug against the product Red Hat En t erp rise Lin u x 5 and against the component Do cu men t at io n -
clu st er.
Be sure to mention the manual identifier:
Cluster_Administration(EN)-5 (2014-6-30T15:52)
By mentioning this manual's identifier, we know exactly which version of the guide you have.
If you have a suggestion for improving the documentation, try to be as specific as possible. If you have found an error, please include the section number and some of the surrounding text so we can find it easily.
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Red Hat Ent erprise Linux 5 Clust er Administ rat ion
Chapter 1. Red Hat Cluster Configuration and Management
Overview
Red Hat Cluster allows you to connect a group of computers (called nodes or members) to work together as a cluster. It provides a wide variety of ways to configure hardware and software to suit your clustering needs (for example, a cluster for sharing files on a GFS file system or a cluster with high-availability service failover). This book provides information about how to use configuration tools to configure your cluster and provides considerations to take into account before deploying a
Red Hat Cluster. To ensure that your deployment of Red Hat Cluster fully meets your needs and can be supported, consult with an authorized Red Hat representative before you deploy it.
1.1. Configurat ion Basics
To set up a cluster, you must connect the nodes to certain cluster hardware and configure the nodes into the cluster environment. This chapter provides an overview of cluster configuration and management, and tools available for configuring and managing a Red Hat Cluster.
Note
For information on best practices for deploying and upgrading Red Hat Enterprise Linux 5
Advanced Platform (Clustering and GFS/GFS2), refer to the article "Red Hat Enterprise Linux
Cluster, High Availability, and GFS Deployment Best Practices" on Red Hat Customer Portal at https://access.redhat.com/site/articles/40051 .
Configuring and managing a Red Hat Cluster consists of the following basic steps:
1. Setting up hardware. Refer to Section 1.1.1, “ Setting Up Hardware” .
3. Configuring Red Hat Cluster Software. Refer to Section 1.1.3, “ Configuring Red Hat Cluster
1.1.1. Set t ing Up Hardware
Setting up hardware consists of connecting cluster nodes to other hardware required to run a Red
Hat Cluster. The amount and type of hardware varies according to the purpose and availability requirements of the cluster. Typically, an enterprise-level cluster requires the following type of
hardware (refer to Figure 1.1, “ Red Hat Cluster Hardware Overview”
).For considerations about hardware and other cluster configuration concerns, refer to "Before Configuring a Red Hat Cluster" or check with an authorized Red Hat representative.
Cluster nodes — Computers that are capable of running Red Hat Enterprise Linux 5 software, with at least 1GB of RAM. The maximum number of nodes supported in a Red Hat Cluster is 16.
Ethernet switch or hub for public network — This is required for client access to the cluster.
Ethernet switch or hub for private network — This is required for communication among the cluster nodes and other cluster hardware such as network power switches and Fibre Channel switches.
Network power switch — A network power switch is recommended to perform fencing in an enterprise-level cluster.
8
Chapt er 1 . Red Hat Clust er Configurat ion and Management O verview
Fibre Channel switch — A Fibre Channel switch provides access to Fibre Channel storage. Other options are available for storage according to the type of storage interface; for example, iSCSI or
GNBD. A Fibre Channel switch can be configured to perform fencing.
Storage — Some type of storage is required for a cluster. The type required depends on the purpose of the cluster.
Fig u re 1.1. Red Hat Clu st er Hard ware O verview
1.1.2. Inst alling Red Hat Clust er soft ware
To install Red Hat Cluster software, you must have entitlements for the software. If you are using the
Co n g a configuration GUI, you can let it install the cluster software. If you are using other tools to configure the cluster, secure and install the software as you would with Red Hat Enterprise Linux software.
1 .1 .2 .1 . Upgrading t he Clust e r So ft ware
It is possible to upgrade the cluster software on a given minor release of Red Hat Enterprise Linux without taking the cluster out of production. Doing so requires disabling the cluster software on one host at a time, upgrading the software, and restarting the cluster software on that host.
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Red Hat Ent erprise Linux 5 Clust er Administ rat ion
1. Shut down all cluster services on a single cluster node. For instructions on stopping cluster software on a node, refer to
Section 6.1, “ Starting and Stopping the Cluster Software”
. It may be desirable to manually relocate cluster-managed services and virtual machines off of the host prior to stopping rgmanager.
2. Execute the yum update command to install the new RPMs. For example: yum update -y openais cman rgmanager lvm2-cluster gfs2-utils
3. Reboot the cluster node or restart the cluster services manually. For instructions on starting
cluster software on a node, refer to Section 6.1, “ Starting and Stopping the Cluster Software” .
1.1.3. Configuring Red Hat Clust er Soft ware
Configuring Red Hat Cluster software consists of using configuration tools to specify the relationship among the cluster components.
Figure 1.2, “ Cluster Configuration Structure”
shows an example of the hierarchical relationship among cluster nodes, high-availability services, and resources. The cluster nodes are connected to one or more fencing devices. Nodes can be grouped into a failover domain for a cluster service. The services comprise resources such as NFS exports, IP addresses, and shared GFS partitions.
Fig u re 1.2. Clu st er Co n f ig u rat io n St ru ct u re
10
Chapt er 1 . Red Hat Clust er Configurat ion and Management O verview
The following cluster configuration tools are available with Red Hat Cluster:
Co n g a — This is a comprehensive user interface for installing, configuring, and managing Red
Hat clusters, computers, and storage attached to clusters and computers.
system-config-cluster — This is a user interface for configuring and managing a Red Hat cluster.
Command line tools — This is a set of command line tools for configuring and managing a Red
Hat cluster.
A brief overview of each configuration tool is provided in the following sections:
Section 1.3, “ system-config-cluster Cluster Administration GUI”
Section 1.4, “ Command Line Administration Tools”
In addition, information about using Co n g a and system-config-cluster is provided in subsequent chapters of this document. Information about the command line tools is available in the man pages for the tools.
1.2. Conga
Co n g a is an integrated set of software components that provides centralized configuration and management of Red Hat clusters and storage. Co n g a provides the following major features:
One Web interface for managing cluster and storage
Automated Deployment of Cluster Data and Supporting Packages
Easy Integration with Existing Clusters
No Need to Re-Authenticate
Integration of Cluster Status and Logs
Fine-Grained Control over User Permissions
The primary components in Co n g a are lu ci and ricci, which are separately installable. lu ci is a server that runs on one computer and communicates with multiple clusters and computers via ricci.
ricci is an agent that runs on each computer (either a cluster member or a standalone computer) managed by Co n g a.
lu ci is accessible through a Web browser and provides three major functions that are accessible through the following tabs:
h o meb ase — Provides tools for adding and deleting computers, adding and deleting users, and configuring user privileges. Only a system administrator is allowed to access this tab.
clu st er — Provides tools for creating and configuring clusters. Each instance of lu ci lists clusters that have been set up with that lu ci. A system administrator can administer all clusters listed on this tab. Other users can administer only clusters that the user has permission to manage (granted by an administrator).
st o rag e — Provides tools for remote administration of storage. With the tools on this tab, you can manage storage on computers whether they belong to a cluster or not.
11
Red Hat Ent erprise Linux 5 Clust er Administ rat ion
To administer a cluster or storage, an administrator adds (or registers) a cluster or a computer to a
lu ci server. When a cluster or a computer is registered with lu ci, the FQDN hostname or IP address of each computer is stored in a lu ci database.
You can populate the database of one lu ci instance from another lu ciinstance. That capability provides a means of replicating a lu ci server instance and provides an efficient upgrade and testing path. When you install an instance of lu ci, its database is empty. However, you can import part or all of a lu ci database from an existing lu ci server when deploying a new lu ci server.
Each lu ci instance has one user at initial installation — admin. Only the admin user may add systems to a lu ci server. Also, the admin user can create additional user accounts and determine which users are allowed to access clusters and computers registered in the lu ci database. It is possible to import users as a batch operation in a new lu ci server, just as it is possible to import clusters and computers.
When a computer is added to a lu ci server to be administered, authentication is done once. No authentication is necessary from then on (unless the certificate used is revoked by a CA). After that, you can remotely configure and manage clusters and storage through the lu ci user interface. lu ci and ricci communicate with each other via XML.
The following figures show sample displays of the three major lu ci tabs: h o meb ase, clu st er, and
st o rag e.
For more information about Co n g a, refer to
Chapter 3, Configuring Red Hat Cluster With Conga ,
Chapter 4, Managing Red Hat Cluster With Conga
, and the online help available with the lu ci server.
Fig u re 1.3. lu ci h o meb ase T ab
12
Fig u re 1.4 . lu ci clu st er T ab
Chapt er 1 . Red Hat Clust er Configurat ion and Management O verview
13
Red Hat Ent erprise Linux 5 Clust er Administ rat ion
Fig u re 1.5. lu ci st o rag e T ab
1.3. system-config-cluster Clust er Administ rat ion GUI
This section provides an overview of the cluster administration graphical user interface (GUI) available with Red Hat Cluster Suite — system-config-cluster. It is for use with the cluster infrastructure and the high-availability service management components. system-config-
cluster consists of two major functions: the Clu st er Co n f ig u rat io n T o o l and the Clu st er
St at u s T o o l. The Clu st er Co n f ig u rat io n T o o l provides the capability to create, edit, and propagate the cluster configuration file ( /etc/cluster/cluster.conf). The Clu st er St at u s
T o o l provides the capability to manage high-availability services. The following sections summarize those functions.
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Chapt er 1 . Red Hat Clust er Configurat ion and Management O verview
Note
While system-config-cluster provides several convenient tools for configuring and managing a Red Hat Cluster, the newer, more comprehensive tool, Co n g a, provides more convenience and flexibility than system-config-cluster.
1.3.1. Clust er Configurat ion T ool
You can access the Clu st er Co n f ig u rat io n T o o l (
Figure 1.6, “ Cluster Configuration Tool” )
through the Cluster Configuration tab in the Cluster Administration GUI.
Fig u re 1.6 . Clu st er Co n f ig u rat io n T o o l
15
Red Hat Ent erprise Linux 5 Clust er Administ rat ion
The Clu st er Co n f ig u rat io n T o o l represents cluster configuration components in the configuration file ( /etc/cluster/cluster.conf) with a hierarchical graphical display in the left panel. A triangle icon to the left of a component name indicates that the component has one or more subordinate components assigned to it. Clicking the triangle icon expands and collapses the portion of the tree below a component. The components displayed in the GUI are summarized as follows:
Cluster Nodes — Displays cluster nodes. Nodes are represented by name as subordinate elements under Cluster Nodes. Using configuration buttons at the bottom of the right frame
(below Properties), you can add nodes, delete nodes, edit node properties, and configure fencing methods for each node.
Fence Devices — Displays fence devices. Fence devices are represented as subordinate elements under Fence Devices. Using configuration buttons at the bottom of the right frame
(below Properties), you can add fence devices, delete fence devices, and edit fence-device properties. Fence devices must be defined before you can configure fencing (with the Manage
Fencing For This Node button) for each node.
Managed Resources — Displays failover domains, resources, and services.
Failover Domains — For configuring one or more subsets of cluster nodes used to run a high-availability service in the event of a node failure. Failover domains are represented as subordinate elements under Failover Domains. Using configuration buttons at the bottom of the right frame (below Properties), you can create failover domains (when Failover
Domains is selected) or edit failover domain properties (when a failover domain is selected).
Resources — For configuring shared resources to be used by high-availability services.
Shared resources consist of file systems, IP addresses, NFS mounts and exports, and usercreated scripts that are available to any high-availability service in the cluster. Resources are represented as subordinate elements under Resources. Using configuration buttons at the bottom of the right frame (below Properties), you can create resources (when Resources is selected) or edit resource properties (when a resource is selected).
Note
The Clu st er Co n f ig u rat io n T o o l provides the capability to configure private resources, also. A private resource is a resource that is configured for use with only one service. You can configure a private resource within a Service component in the GUI.
Services — For creating and configuring high-availability services. A service is configured by assigning resources (shared or private), assigning a failover domain, and defining a recovery policy for the service. Services are represented as subordinate elements under
Services. Using configuration buttons at the bottom of the right frame (below Properties), you can create services (when Services is selected) or edit service properties (when a service is selected).
1.3.2. Clust er St at us T ool
You can access the Clu st er St at u s T o o l (
Figure 1.7, “ Cluster Status Tool”
) through the Clu st er
Man ag emen t tab in Cluster Administration GUI.
16
Chapt er 1 . Red Hat Clust er Configurat ion and Management O verview
Fig u re 1.7. Clu st er St at u s T o o l
The nodes and services displayed in the Clu st er St at u s T o o l are determined by the cluster configuration file ( /etc/cluster/cluster.conf). You can use the Clu st er St at u s T o o l to enable, disable, restart, or relocate a high-availability service.
1.4 . Command Line Administ rat ion T ools
In addition to Co n g a and the system-config-cluster Cluster Administration GUI, command line tools are available for administering the cluster infrastructure and the high-availability service management components. The command line tools are used by the Cluster Administration GUI and init scripts supplied by Red Hat.
Table 1.1, “ Command Line Tools”
summarizes the command line tools.
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Red Hat Ent erprise Linux 5 Clust er Administ rat ion
T ab le 1.1. Co mman d Lin e T o o ls
Co mman d Lin e
T o o l
ccs_tool —
Cluster
Configuration
System Tool
cman_tool —
Cluster
Management Tool
fence_tool —
Fence Tool
clustat —
Cluster Status
Utility
clusvcadm —
Cluster User
Service
Administration
Utility
Used Wit h
Cluster
Infrastructure
Cluster
Infrastructure
Cluster
Infrastructure
High-availability
Service
Management
Components
High-availability
Service
Management
Components
Pu rp o se
ccs_tool is a program for making online updates to the cluster configuration file. It provides the capability to create and modify cluster infrastructure components (for example, creating a cluster, adding and removing a node).
For more information about this tool, refer to the ccs_tool(8) man page.
cman_tool is a program that manages the CMAN cluster manager. It provides the capability to join a cluster, leave a cluster, kill a node, or change the expected quorum votes of a node in a cluster. For more information about this tool, refer to the cman_tool(8) man page.
fence_tool is a program used to join or leave the default fence domain. Specifically, it starts the fence daemon
(fenced) to join the domain and kills fenced to leave the domain. For more information about this tool, refer to the fence_tool(8) man page.
The clustat command displays the status of the cluster.
It shows membership information, quorum view, and the state of all configured user services. For more information about this tool, refer to the clustat(8) man page.
The clusvcadm command allows you to enable, disable, relocate, and restart high-availability services in a cluster.
For more information about this tool, refer to the clusvcadm(8) man page.
18
Chapt er 2 . Before Configuring a Red Hat Clust er
Chapter 2. Before Configuring a Red Hat Cluster
This chapter describes tasks to perform and considerations to make before installing and configuring a Red Hat Cluster, and consists of the following sections.
Important
Make sure that your deployment of Red Hat Cluster Suite meets your needs and can be supported. Consult with an authorized Red Hat representative to verify Cluster Suite and GFS configuration prior to deployment. In addition, allow time for a configuration burn-in period to test failure modes.
Section 2.1, “ General Configuration Considerations”
Section 2.2, “ Compatible Hardware”
Section 2.3, “ Enabling IP Ports”
Section 2.4, “ Configuring ACPI For Use with Integrated Fence Devices”
Section 2.6, “ Configuring max_luns”
Section 2.7, “ Considerations for Using Quorum Disk”
Section 2.8, “ Red Hat Cluster Suite and SELinux”
Section 2.9, “ Multicast Addresses”
Section 2.10, “ Configuring the iptables Firewall to Allow Cluster Components”
Section 2.11, “ Considerations for Using Co n g a”
Section 2.12, “ Configuring Virtual Machines in a Clustered Environment”
2.1. General Configurat ion Considerat ions
You can configure a Red Hat Cluster in a variety of ways to suit your needs. Take into account the following general considerations when you plan, configure, and implement your Red Hat Cluster.
Nu mb er o f clu st er n o d es su p p o rt ed
The maximum number of nodes supported in a Red Hat Cluster is 16.
G FS/G FS2
Although a GFS/GFS2 file system can be implemented in a standalone system or as part of a cluster configuration, for the RHEL 5.5 release and later, Red Hat does not support the use of GFS/GFS2 as a single-node file system. Red Hat does support a number of highperformance single-node file systems that are optimized for single node, and thus have generally lower overhead than a cluster file system. Red Hat recommends using those file systems in preference to GFS/GFS2 in cases where only a single node needs to mount the file system. Red Hat will continue to support single-node GFS/GFS2 file systems for existing customers.
When you configure a GFS/GFS2 file system as a cluster file system, you must ensure that all nodes in the cluster have access to the shared file system. Asymmetric cluster
19
Red Hat Ent erprise Linux 5 Clust er Administ rat ion configurations in which some nodes have access to the file system and others do not are not supported.This does not require that all nodes actually mount the GFS/GFS2 file system itself.
No - sin g le- p o in t - o f - f ailu re h ard ware co n f ig u rat io n
Clusters can include a dual-controller RAID array, multiple bonded network channels, multiple paths between cluster members and storage, and redundant un-interruptible power supply (UPS) systems to ensure that no single failure results in application down time or loss of data.
Alternatively, a low-cost cluster can be set up to provide less availability than a no-singlepoint-of-failure cluster. For example, you can set up a cluster with a single-controller RAID array and only a single Ethernet channel.
Certain low-cost alternatives, such as host RAID controllers, software RAID without cluster support, and multi-initiator parallel SCSI configurations are not compatible or appropriate for use as shared cluster storage.
Dat a in t eg rit y assu ran ce
To ensure data integrity, only one node can run a cluster service and access clusterservice data at a time. The use of power switches in the cluster hardware configuration enables a node to power-cycle another node before restarting that node's HA services during a failover process. This prevents two nodes from simultaneously accessing the same data and corrupting it. It is strongly recommended that fence devices (hardware or software solutions that remotely power, shutdown, and reboot cluster nodes) are used to guarantee data integrity under all failure conditions. Watchdog timers provide an alternative way to to ensure correct operation of HA service failover.
Et h ern et ch an n el b o n d in g
Cluster quorum and node health is determined by communication of messages among cluster nodes via Ethernet. In addition, cluster nodes use Ethernet for a variety of other critical cluster functions (for example, fencing). With Ethernet channel bonding, multiple
Ethernet interfaces are configured to behave as one, reducing the risk of a single-point-offailure in the typical switched Ethernet connection among cluster nodes and other cluster hardware.
Red Hat Enterprise Linux 5 supports bonding mode 1 only. It is recommended that you wire each node's slaves to the switches in a consistent manner, with each node's primary device wired to switch 1 and each node's backup device wired to switch 2.
2.2. Compat ible Hardware
Before configuring Red Hat Cluster software, make sure that your cluster uses appropriate hardware
(for example, supported fence devices, storage devices, and Fibre Channel switches). Refer to the
Red Hat Hardware Catalog at https://hardware.redhat.com/ for the most current hardware compatibility information.
2.3. Enabling IP Port s
Before deploying a Red Hat Cluster, you must enable certain IP ports on the cluster nodes and on computers that run lu ci (the Co n g a user interface server). The following sections identify the IP ports to be enabled:
20
Chapt er 2 . Before Configuring a Red Hat Clust er
Section 2.3.1, “ Enabling IP Ports on Cluster Nodes”
Section 2.3.2, “ Enabling IP Ports on Computers That Run lu ci”
2.3.1. Enabling IP Port s on Clust er Nodes
To allow Red Hat Cluster nodes to communicate with each other, you must enable the IP ports
assigned to certain Red Hat Cluster components. Table 2.1, “ Enabled IP Ports on Red Hat Cluster
Ports on Red Hat Cluster Nodes” .
Note
IPV6 is not supported for Cluster Suite in Red Hat Enterprise Linux 5.
T ab le 2.1. En ab led IP Po rt s o n Red Hat Clu st er No d es
IP Po rt Nu mb er Pro t o co l
5404, 5405
11111
14567
16851
21064
50006, 50008,
50009
50007
UDP
TCP
TCP
TCP
TCP
TCP
UDP
Co mp o n en t
cman (Cluster Manager)
ricci (part of Co n g a remote agent)
gnbd (Global Network Block Device)
modclusterd (part of Co n g a remote agent)
dlm (Distributed Lock Manager)
ccsd (Cluster Configuration System daemon)
ccsd (Cluster Configuration System daemon)
Note
Table 2.1, “ Enabled IP Ports on Red Hat Cluster Nodes” shows no IP ports to enable for
rgmanager. For Red Hat Enterprise Linux 5.1 and later, rgmanager does not use TCP or
UDP sockets.
2.3.2. Enabling IP Port s on Comput ers T hat Run luci
To allow client computers to communicate with a computer that runs lu ci (the Co n g a user interface server), and to allow a computer that runs lu ci to communicate with ricci in the cluster nodes, you
Nodes” lists the IP port numbers, their respective protocols, and the components to which the port
numbers are assigned. At each computer that runs lu ci, enable IP ports according to Table 2.2,
“ Enabled IP Ports on a Computer That Runs luci” .
Note
If a cluster node is running lu ci, port 11111 should already have been enabled.
21
Red Hat Ent erprise Linux 5 Clust er Administ rat ion
T ab le 2.2. En ab led IP Po rt s o n a Co mp u t er T h at Ru n s lu ci
IP Po rt Nu mb er
8084
11111
Pro t o co l
TCP
TCP
Co mp o n en t
lu ci (Co n g a user interface server)
ricci (Co n g a remote agent)
If your server infrastructure incorporates more than one network and you want to access lu ci from the internal network only, you can configure the st u n n el component to listen on one IP address only by editing the LUCI_HTTPS_PORT parameter in the /etc/sysconfig/luci file as follows:
LUCI_HTTPS_PORT=10.10.10.10:8084
2.4 . Configuring ACPI For Use wit h Int egrat ed Fence Devices
If your cluster uses integrated fence devices, you must configure ACPI (Advanced Configuration and
Power Interface) to ensure immediate and complete fencing.
Note
For the most current information about integrated fence devices supported by Red Hat Cluster
Suite, refer to http://www.redhat.com/cluster_suite/hardware/ .
If a cluster node is configured to be fenced by an integrated fence device, disable ACPI Soft-Off for that node. Disabling ACPI Soft-Off allows an integrated fence device to turn off a node immediately and completely rather than attempting a clean shutdown (for example, shutdown -h now).
Otherwise, if ACPI Soft-Off is enabled, an integrated fence device can take four or more seconds to turn off a node (refer to note that follows). In addition, if ACPI Soft-Off is enabled and a node panics or freezes during shutdown, an integrated fence device may not be able to turn off the node. Under those circumstances, fencing is delayed or unsuccessful. Consequently, when a node is fenced with an integrated fence device and ACPI Soft-Off is enabled, a cluster recovers slowly or requires administrative intervention to recover.
Note
The amount of time required to fence a node depends on the integrated fence device used.
Some integrated fence devices perform the equivalent of pressing and holding the power button; therefore, the fence device turns off the node in four to five seconds. Other integrated fence devices perform the equivalent of pressing the power button momentarily, relying on the operating system to turn off the node; therefore, the fence device turns off the node in a time span much longer than four to five seconds.
To disable ACPI Soft-Off, use chkconfig management and verify that the node turns off immediately when fenced. The preferred way to disable ACPI Soft-Off is with chkconfig management: however, if that method is not satisfactory for your cluster, you can disable ACPI Soft-Off with one of the following alternate methods:
Changing the BIOS setting to "instant-off" or an equivalent setting that turns off the node without delay
22
Chapt er 2 . Before Configuring a Red Hat Clust er
Note
Disabling ACPI Soft-Off with the BIOS may not be possible with some computers.
Appending acpi=off to the kernel boot command line of the /boot/grub/grub.conf file
Important
This method completely disables ACPI; some computers do not boot correctly if ACPI is completely disabled. Use this method only if the other methods are not effective for your cluster.
The following sections provide procedures for the preferred method and alternate methods of disabling ACPI Soft-Off:
Section 2.4.1, “ Disabling ACPI Soft-Off with chkconfig Management” — Preferred method
Section 2.4.2, “ Disabling ACPI Soft-Off with the BIOS” — First alternate method
Section 2.4.3, “ Disabling ACPI Completely in the grub.conf File” — Second alternate method
2.4 .1. Disabling ACPI Soft -Off wit h chkconfig Management
You can use chkconfig management to disable ACPI Soft-Off either by removing the ACPI daemon
( acpid) from chkconfig management or by turning off acpid.
Note
This is the preferred method of disabling ACPI Soft-Off.
Disable ACPI Soft-Off with chkconfig management at each cluster node as follows:
1. Run either of the following commands:
chkconfig --del acpid — This command removes acpid from chkconfig management.
— OR —
chkconfig --level 2345 acpid off — This command turns off acpid.
2. Reboot the node.
3. When the cluster is configured and running, verify that the node turns off immediately when fenced.
23
Red Hat Ent erprise Linux 5 Clust er Administ rat ion
Note
You can fence the node with the fence_node command or Co n g a.
2.4 .2. Disabling ACPI Soft -Off wit h t he BIOS
The preferred method of disabling ACPI Soft-Off is with chkconfig management ( Section 2.4.1,
“ Disabling ACPI Soft-Off with chkconfig Management” ). However, if the preferred method is not
effective for your cluster, follow the procedure in this section.
Note
Disabling ACPI Soft-Off with the BIOS may not be possible with some computers.
You can disable ACPI Soft-Off by configuring the BIOS of each cluster node as follows:
1. Reboot the node and start the BIOS CMOS Setup Utility program.
2. Navigate to the Po wer menu (or equivalent power management menu).
3. At the Po wer menu, set the So f t - O f f b y PWR- BT T N function (or equivalent) to In st an t -
O f f (or the equivalent setting that turns off the node via the power button without delay).
Example 2.1, “ BIOS CMOS Setup Utility: Soft-Off by PWR-BTTN set to Instant-Off”
shows a Po wer menu with ACPI Fu n ct io n set to En ab led and So f t - O f f b y PWR- BT T N set to In st an t - O f f .
Note
The equivalents to ACPI Fu n ct io n , So f t - O f f b y PWR- BT T N, and In st an t - O f f may vary among computers. However, the objective of this procedure is to configure the
BIOS so that the computer is turned off via the power button without delay.
4. Exit the BIOS CMOS Setup Utility program, saving the BIOS configuration.
5. When the cluster is configured and running, verify that the node turns off immediately when fenced.
Note
You can fence the node with the fence_node command or Co n g a.
24
Examp le 2.1. BIOS CMOS Setup Utility: So f t - O f f b y PWR- BT T N set t o In st an t - O f f
+---------------------------------------------|-------------------+
| ACPI Function [Enabled] | Item Help |
| ACPI Suspend Type [S1(POS)] |-------------------|
| x Run VGABIOS if S3 Resume Auto | Menu Level * |
Chapt er 2 . Before Configuring a Red Hat Clust er
| Suspend Mode [Disabled] | |
| HDD Power Down [Disabled] | |
| Soft-Off by PWR-BTTN [Instant-Off | |
| CPU THRM-Throttling [50.0%] | |
| Wake-Up by PCI card [Enabled] | |
| Power On by Ring [Enabled] | |
| Wake Up On LAN [Enabled] | |
| x USB KB Wake-Up From S3 Disabled | |
| Resume by Alarm [Disabled] | |
| x Date(of Month) Alarm 0 | |
| x Time(hh:mm:ss) Alarm 0 : 0 : | |
| POWER ON Function [BUTTON ONLY | |
| x KB Power ON Password Enter | |
| x Hot Key Power ON Ctrl-F1 | |
| | |
| | |
+---------------------------------------------|-------------------+
This example shows ACPI Fu n ct io n set to En ab led , and So f t - O f f b y PWR- BT T N set to
In st an t - O f f .
2.4 .3. Disabling ACPI Complet ely in t he grub.conf File
The preferred method of disabling ACPI Soft-Off is with chkconfig management ( Section 2.4.1,
“ Disabling ACPI Soft-Off with chkconfig Management” ). If the preferred method is not effective for
your cluster, you can disable ACPI Soft-Off with the BIOS power management ( Section 2.4.2,
can disable ACPI completely by appending acpi=off to the kernel boot command line in the
grub.conf file.
Important
This method completely disables ACPI; some computers do not boot correctly if ACPI is completely disabled. Use this method only if the other methods are not effective for your cluster.
You can disable ACPI completely by editing the grub.conf file of each cluster node as follows:
1. Open /boot/grub/grub.conf with a text editor.
2. Append acpi=off to the kernel boot command line in /boot/grub/grub.conf (refer to
Example 2.2, “ Kernel Boot Command Line with acpi=off Appended to It”
).
3. Reboot the node.
4. When the cluster is configured and running, verify that the node turns off immediately when fenced.
Note
You can fence the node with the fence_node command or Co n g a.
Examp le 2.2. Kern el Bo o t Co mman d Lin e wit h acpi=off Ap p en d ed t o It
25
Red Hat Ent erprise Linux 5 Clust er Administ rat ion
# grub.conf generated by anaconda
#
# Note that you do not have to rerun grub after making changes to this file
# NOTICE: You have a /boot partition. This means that
# all kernel and initrd paths are relative to /boot/, eg.
# root (hd0,0)
# kernel /vmlinuz-version ro root=/dev/VolGroup00/LogVol00
# initrd /initrd-version.img
#boot=/dev/hda default=0 timeout=5 serial --unit=0 --speed=115200 terminal --timeout=5 serial console title Red Hat Enterprise Linux Server (2.6.18-36.el5)
root (hd0,0)
kernel /vmlinuz-2.6.18-36.el5 ro root=/dev/VolGroup00/LogVol00 console=ttyS0,115200n8 acpi=off
initrd /initrd-2.6.18-36.el5.img
In this example, acpi=off has been appended to the kernel boot command line — the line starting with "kernel /vmlinuz-2.6.18-36.el5".
2.5. Considerat ions for Configuring HA Services
You can create a cluster to suit your needs for high availability by configuring HA (high-availability) services. The key component for HA service management in a Red Hat cluster, rgmanager, implements cold failover for off-the-shelf applications. In a Red Hat cluster, an application is configured with other cluster resources to form an HA service that can fail over from one cluster node to another with no apparent interruption to cluster clients. HA-service failover can occur if a cluster node fails or if a cluster system administrator moves the service from one cluster node to another (for example, for a planned outage of a cluster node).
To create an HA service, you must configure it in the cluster configuration file. An HA service comprises cluster resources. Cluster resources are building blocks that you create and manage in the cluster configuration file — for example, an IP address, an application initialization script, or a Red
Hat GFS shared partition.
An HA service can run on only one cluster node at a time to maintain data integrity. You can specify failover priority in a failover domain. Specifying failover priority consists of assigning a priority level to each node in a failover domain. The priority level determines the failover order — determining which node that an HA service should fail over to. If you do not specify failover priority, an HA service can fail over to any node in its failover domain. Also, you can specify if an HA service is restricted to run only on nodes of its associated failover domain. (When associated with an unrestricted failover domain, an HA service can start on any cluster node in the event no member of the failover domain is available.)
Figure 2.1, “ Web Server Cluster Service Example” shows an example of an HA service that is a web
server named "content-webserver". It is running in cluster node B and is in a failover domain that consists of nodes A, B, and D. In addition, the failover domain is configured with a failover priority to fail over to node D before node A and to restrict failover to nodes only in that failover domain. The HA service comprises these cluster resources:
IP address resource — IP address 10.10.10.201.
An application resource named "httpd-content" — a web server application init script
/etc/init.d/httpd (specifying httpd).
A file system resource — Red Hat GFS named "gfs-content-webserver".
26
Chapt er 2 . Before Configuring a Red Hat Clust er
Fig u re 2.1. Web Server Clu st er Service Examp le
Clients access the HA service through the IP address 10.10.10.201, enabling interaction with the web server application, httpd-content. The httpd-content application uses the gfs-content-webserver file system. If node B were to fail, the content-webserver HA service would fail over to node D. If node D were not available or also failed, the service would fail over to node A. Failover would occur with minimal service interruption to the cluster clients. For example, in an HTTP service, certain state information may be lost (like session data). The HA service would be accessible from another cluster node via the same IP address as it was before failover.
Note
For more information about HA services and failover domains, refer to Red Hat Cluster Suite
Overview. For information about configuring failover domains, refer to Section 3.7,
“ Configuring a Failover Domain” (using Co n g a) or
Section 5.6, “ Configuring a Failover
Domain” (using system-config-cluster).
27
Red Hat Ent erprise Linux 5 Clust er Administ rat ion
An HA service is a group of cluster resources configured into a coherent entity that provides specialized services to clients. An HA service is represented as a resource tree in the cluster configuration file, /etc/cluster/cluster.conf (in each cluster node). In the cluster configuration file, each resource tree is an XML representation that specifies each resource, its attributes, and its relationship among other resources in the resource tree (parent, child, and sibling relationships).
Note
Because an HA service consists of resources organized into a hierarchical tree, a service is sometimes referred to as a resource tree or resource group. Both phrases are synonymous with
HA service.
At the root of each resource tree is a special type of resource — a service resource. Other types of resources comprise the rest of a service, determining its characteristics. Configuring an HA service consists of creating a service resource, creating subordinate cluster resources, and organizing them into a coherent entity that conforms to hierarchical restrictions of the service.
Red Hat Cluster supports the following HA services:
Apache
Application (Script)
LVM (HA LVM)
MySQL
NFS
Open LDAP
Oracle
PostgreSQL 8
Samba
Note
Red Hat Enterprise Linux 5 does not support running Clustered Samba in an active/active configuration, in which Samba serves the same shared file system from multiple nodes. Red
Hat Enterprise Linux 5 does support running Samba in a cluster in active/passive mode, with failover from one node to the other nodes in a cluster. Note that if failover occurs, locking states are lost and active connections to Samba are severed so that the clients must reconnect.
SAP
Tomcat 5
There are two major considerations to take into account when configuring an HA service:
The types of resources needed to create a service
28
Chapt er 2 . Before Configuring a Red Hat Clust er
Parent, child, and sibling relationships among resources
The types of resources and the hierarchy of resources depend on the type of service you are configuring.
The types of cluster resources are listed in Appendix C, HA Resource Parameters
. Information about
parent, child, and sibling relationships among resources is described in Appendix D, HA Resource
2.6. Configuring max_luns
It is not necessary to configure max_luns in Red Hat Enterprise Linux 5.
In Red Hat Enterprise Linux releases prior to Red Hat Enterprise Linux 5, if RAID storage in a cluster presents multiple LUNs, it is necessary to enable access to those LUNs by configuring max_luns (or
max_scsi_luns for 2.4 kernels) in the /etc/modprobe.conf file of each node. In Red Hat
Enterprise Linux 5, cluster nodes detect multiple LUNs without intervention required; it is not necessary to configure max_luns to detect multiple LUNs.
2.7. Considerat ions for Using Quorum Disk
Quorum Disk is a disk-based quorum daemon, qdiskd, that provides supplemental heuristics to determine node fitness. With heuristics you can determine factors that are important to the operation of the node in the event of a network partition. For example, in a four-node cluster with a 3:1 split, ordinarily, the three nodes automatically "win" because of the three-to-one majority. Under those circumstances, the one node is fenced. With qdiskd however, you can set up heuristics that allow the one node to win based on access to a critical resource (for example, a critical network path). If your cluster requires additional methods of determining node health, then you should configure
qdiskd to meet those needs.
Note
Configuring qdiskd is not required unless you have special requirements for node health. An example of a special requirement is an "all-but-one" configuration. In an all-but-one configuration, qdiskd is configured to provide enough quorum votes to maintain quorum even though only one node is working.
Important
Overall, heuristics and other qdiskd parameters for your Red Hat Cluster depend on the site environment and special requirements needed. To understand the use of heuristics and other
qdiskd parameters, refer to the qdisk(5) man page. If you require assistance understanding and using qdiskd for your site, contact an authorized Red Hat support representative.
If you need to use qdiskd, you should take into account the following considerations:
Clu st er n o d e vo t es
Each cluster node should have the same number of votes.
29
Red Hat Ent erprise Linux 5 Clust er Administ rat ion
CMAN memb ersh ip t imeo u t valu e
The CMAN membership timeout value (the time a node needs to be unresponsive before
CMAN considers that node to be dead, and not a member) should be at least two times that of the qdiskd membership timeout value. The reason is because the quorum daemon must detect failed nodes on its own, and can take much longer to do so than CMAN. The default value for CMAN membership timeout is 10 seconds. Other site-specific conditions may affect the relationship between the membership timeout values of CMAN and qdiskd. For assistance with adjusting the CMAN membership timeout value, contact an authorized Red
Hat support representative.
Fen cin g
To ensure reliable fencing when using qdiskd, use power fencing. While other types of fencing (such as watchdog timers and software-based solutions to reboot a node internally) can be reliable for clusters not configured with qdiskd, they are not reliable for a cluster configured with qdiskd.
Maximu m n o d es
A cluster configured with qdiskd supports a maximum of 16 nodes. The reason for the limit is because of scalability; increasing the node count increases the amount of synchronous
I/O contention on the shared quorum disk device.
Q u o ru m d isk d evice
A quorum disk device should be a shared block device with concurrent read/write access by all nodes in a cluster. The minimum size of the block device is 10 Megabytes. Examples of shared block devices that can be used by qdiskd are a multi-port SCSI RAID array, a
Fibre Channel RAID SAN, or a RAID-configured iSCSI target. You can create a quorum disk device with mkqdisk, the Cluster Quorum Disk Utility. For information about using the utility refer to the mkqdisk(8) man page.
Note
Using JBOD as a quorum disk is not recommended. A JBOD cannot provide dependable performance and therefore may not allow a node to write to it quickly enough. If a node is unable to write to a quorum disk device quickly enough, the node is falsely evicted from a cluster.
2.8. Red Hat Clust er Suit e and SELinux
Red Hat Cluster Suite supports SELinux states according to the Red Hat Enterprise Linux release level deployed in your cluster as follows:
Red Hat Enterprise Linux 5.4 and earlier — disabled state only.
Red Hat Enterprise Linux 5.5 and later — enforcing or permissive state with the SELinux policy type set to targeted (or with the state set to disabled).
30
Chapt er 2 . Before Configuring a Red Hat Clust er
Note
When using SELinux with Red Hat Cluster Suite in a VM environment, you should ensure that the SELinux boolean fenced_can_network_connect is persistently set to on. This allows the fence_xvm fencing agent to work properly, enabling the system to fence virtual machines.
For more information about SELinux, refer to Deployment Guide for Red Hat Enterprise Linux 5.
2.9. Mult icast Addresses
Red Hat Cluster nodes communicate among each other using multicast addresses. Therefore, each network switch and associated networking equipment in a Red Hat Cluster must be configured to enable multicast addresses and support IGMP (Internet Group Management Protocol). Ensure that each network switch and associated networking equipment in a Red Hat Cluster are capable of supporting multicast addresses and IGMP; if they are, ensure that multicast addressing and IGMP are enabled. Without multicast and IGMP, not all nodes can participate in a cluster, causing the cluster to fail.
Note
Procedures for configuring network switches and associated networking equipment vary according each product. Refer to the appropriate vendor documentation or other information about configuring network switches and associated networking equipment to enable multicast addresses and IGMP.
Note
IPV6 is not supported for Cluster Suite in Red Hat Enterprise Linux 5.
2.10. Configuring t he ipt ables Firewall t o Allow Clust er Component s
You can use the following filtering to allow multicast traffic through the iptables firewall for the various cluster components.
For openais, use the following filtering. Port 5405 is used to receive multicast traffic.
iptables -I INPUT -p udp -m state --state NEW -m multiport --dports 5404,5405 -j
ACCEPT
For ricci: iptables -I INPUT -p tcp -m state --state NEW -m multiport --dports 11111 -j ACCEPT
For modcluster: iptables -I INPUT -p tcp -m state --state NEW -m multiport --dports 16851 -j ACCEPT
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Red Hat Ent erprise Linux 5 Clust er Administ rat ion
For gnbd: iptables -I INPUT -p tcp -m state --state NEW -m multiport --dports 14567 -j ACCEPT
For luci: iptables -I INPUT -p tcp -m state --state NEW -m multiport --dports 8084 -j ACCEPT
For DLM: iptables -I INPUT -p tcp -m state --state NEW -m multiport --dports 21064 -j ACCEPT
For ccsd: iptables -I INPUT -p udp -m state --state NEW -m multiport --dports 50007 -j ACCEPT iptables -I INPUT -p tcp -m state --state NEW -m multiport --dports 50008 -j ACCEPT
After executing these commands, run the following command.
service iptables save ; service iptables restart
In Red Hat Enterprise Linux 5, rgmanager does not access the network directly; rgmanager communication happens by means of openais network transport. Enabling openais allows
rgmanager (or any openais clients) to work automatically.
2.11. Considerat ions for Using Conga
When using Co n g a to configure and manage your Red Hat Cluster, make sure that each computer running lu ci (the Co n g a user interface server) is running on the same network that the cluster is using for cluster communication. Otherwise, lu ci cannot configure the nodes to communicate on the right network. If the computer running lu ci is on another network (for example, a public network rather than a private network that the cluster is communicating on), contact an authorized Red Hat support representative to make sure that the appropriate host name is configured for each cluster node.
2.12. Configuring Virt ual Machines in a Clust ered Environment
When you configure your cluster with virtual machine resources, you should use the rgmanager tools to start and stop the virtual machines. Using xm or virsh to start the machine can result in the virtual machine running in more than one place, which can cause data corruption in the virtual machine.
To reduce the chances of administrators accidentally "double-starting" virtual machines by using both cluster and non-cluster tools in a clustered environment, you can configure your system as follows:
Ensure that you are using the rgmanager 2.0.52-1.el5_4.3 or later package release.
Store the virtual machine configuration files in a non-default location.
Storing the virtual machine configuration files somewhere other than their default location makes it more difficult to accidentally start a virtual machine using xm or virsh, as the configuration file will be unknown out of the box to libvirt or the xm tool.
32
Chapt er 2 . Before Configuring a Red Hat Clust er
The non-default location for virtual machine configuration files may be anywhere. The advantage of using an NFS share or a shared GFS or GFS2 file system is that the administrator does not need to keep the configuration files in sync across the cluster members. However, it is also permissible to use a local directory as long as the administrator keeps the contents synchronized somehow clusterwide.
In the cluster configuration, virtual machines may reference this non-default location by using the
path attribute of a virtual machine resource. Note that the path attribute is a directory or set of directories separated by the colon ':' character, not a path to a specific file.
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Red Hat Ent erprise Linux 5 Clust er Administ rat ion
Chapter 3. Configuring Red Hat Cluster With Conga
This chapter describes how to configure Red Hat Cluster software using Co n g a, and consists of the following sections:
Section 3.1, “ Configuration Tasks”
Section 3.2, “ Starting lu ci and ricci”
Section 3.3, “ Creating A Cluster”
Section 3.4, “ Global Cluster Properties”
Section 3.5, “ Configuring Fence Devices”
Section 3.6, “ Configuring Cluster Members”
Section 3.7, “ Configuring a Failover Domain”
Section 3.8, “ Adding Cluster Resources”
Section 3.9, “ Adding a Cluster Service to the Cluster”
Section 3.10, “ Configuring Cluster Storage”
3.1. Configurat ion T asks
Configuring Red Hat Cluster software with Co n g a consists of the following steps:
1. Configuring and running the Co n g a configuration user interface — the lu ci server. Refer to
Section 3.2, “ Starting lu ci and ricci” .
2. Creating a cluster. Refer to
Section 3.3, “ Creating A Cluster”
.
3. Configuring global cluster properties. Refer to Section 3.4, “ Global Cluster Properties” .
4. Configuring fence devices. Refer to Section 3.5, “ Configuring Fence Devices” .
5. Configuring cluster members. Refer to Section 3.6, “ Configuring Cluster Members”
.
6. Creating failover domains. Refer to
Section 3.7, “ Configuring a Failover Domain” .
7. Creating resources. Refer to Section 3.8, “ Adding Cluster Resources” .
8. Creating cluster services. Refer to
Section 3.9, “ Adding a Cluster Service to the Cluster”
.
9. Configuring storage. Refer to
Section 3.10, “ Configuring Cluster Storage” .
3.2. St art ing luci and ricci
To administer Red Hat Clusters with Co n g a, install and run lu ci and ricci as follows:
1. At each node to be administered by Co n g a, install the ricci agent. For example:
# yum install ricci
2. At each node to be administered by Co n g a, start ricci. For example:
34
Chapt er 3. Configuring Red Hat Clust er Wit h Conga
# service ricci start
Starting ricci: [ OK ]
3. Select a computer to host lu ci and install the lu ci software on that computer. For example:
# yum install luci
Note
Typically, a computer in a server cage or a data center hosts lu ci; however, a cluster computer can host lu ci.
4. At the computer running lu ci, initialize the lu ci server using the luci_admin init command. For example:
# luci_admin init
Initializing the Luci server
Creating the 'admin' user
Enter password: <Type password and press ENTER.>
Confirm password: <Re-type password and press ENTER.>
Please wait...
The admin password has been successfully set.
Generating SSL certificates...
Luci server has been successfully initialized
Restart the Luci server for changes to take effect eg. service luci restart
5. Start lu ci using service luci restart. For example:
# service luci restart
Shutting down luci: [ OK ]
Starting luci: generating https SSL certificates... done
[ OK ]
Please, point your web browser to https://nano-01:8084 to access luci
6. At a Web browser, place the URL of the lu ci server into the URL address box and click G o (or the equivalent). The URL syntax for the lu ci server is
https://luci_server_hostname:8084. The first time you access lu ci, two SSL certificate dialog boxes are displayed. Upon acknowledging the dialog boxes, your Web browser displays the lu ci login page.
3.3. Creat ing A Clust er
Creating a cluster with lu ci consists of selecting cluster nodes, entering their passwords, and submitting the request to create a cluster. If the node information and passwords are correct, Co n g a automatically installs software into the cluster nodes and starts the cluster. Create a cluster as follows:
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Red Hat Ent erprise Linux 5 Clust er Administ rat ion
1. As administrator of lu ci, select the clu st er tab.
2. Click Creat e a New Clu st er.
3. At the Clu st er Name text box, enter a cluster name. The cluster name cannot exceed 15 characters. Add the node name and password for each cluster node. Enter the node name for each node in the No d e Ho st n ame column; enter the root password for each node in the
Ro o t Passwo rd column. Check the En ab le Sh ared St o rag e Su p p o rt checkbox if clustered storage is required.
4. Click Submit. Clicking Submit causes the following actions: a. Cluster software packages to be downloaded onto each cluster node.
b. Cluster software to be installed onto each cluster node.
c. Cluster configuration file to be created and propagated to each node in the cluster.
d. Starting the cluster.
A progress page shows the progress of those actions for each node in the cluster.
When the process of creating a new cluster is complete, a page is displayed providing a configuration interface for the newly created cluster.
3.4 . Global Clust er Propert ies
When a cluster is created, or if you select a cluster to configure, a cluster-specific page is displayed.
The page provides an interface for configuring cluster-wide properties and detailed properties. You can configure cluster-wide properties with the tabbed interface below the cluster name. The interface provides the following tabs: G en eral, Fen ce, Mu lt icast , and Q u o ru m Part it io n . To configure the parameters in those tabs, follow the steps in this section. If you do not need to configure parameters in a tab, skip the step for that tab.
1. G en eral tab — This tab displays cluster name and provides an interface for configuring the configuration version and advanced cluster properties. The parameters are summarized as follows:
The Clu st er Name text box displays the cluster name; it does not accept a cluster name change. You cannot change the cluster name. The only way to change the name of a Red
Hat cluster is to create a new cluster configuration with the new name.
The Co n f ig u rat io n Versio n value is set to 1 by default and is automatically incremented each time you modify your cluster configuration. However, if you need to set it to another value, you can specify it at the Co n f ig u rat io n Versio n text box.
You can enter advanced cluster properties by clicking Sh o w ad van ced clu st er
p ro p ert ies. Clicking Sh o w ad van ced clu st er p ro p ert ies reveals a list of advanced properties. You can click any advanced property for online help about the property.
Enter the values required and click Apply for changes to take effect.
2. Fen ce tab — This tab provides an interface for configuring these Fen ce Daemo n
Pro p ert ies parameters: Po st - Fail Delay and Po st - Jo in Delay. The parameters are summarized as follows:
36
Chapt er 3. Configuring Red Hat Clust er Wit h Conga
The Po st - Fail Delay parameter is the number of seconds the fence daemon ( fenced) waits before fencing a node (a member of the fence domain) after the node has failed. The
Po st - Fail Delay default value is 0. Its value may be varied to suit cluster and network performance.
The Po st - Jo in Delay parameter is the number of seconds the fence daemon ( fenced) waits before fencing a node after the node joins the fence domain. The Po st - Jo in Delay default value is 3. A typical setting for Po st - Jo in Delay is between 20 and 30 seconds, but can vary according to cluster and network performance.
Enter values required and Click Apply for changes to take effect.
Note
For more information about Po st - Jo in Delay and Po st - Fail Delay, refer to the fenced(8) man page.
3. Mu lt icast tab — This tab provides an interface for configuring these Mu lt icast
Co n f ig u rat io n parameters: Let clu st er ch o o se t h e mu lt icast ad d ress and Sp ecif y
t h e mu lt icast ad d ress man u ally. The default setting is Let clu st er ch o o se t h e
mu lt icast ad d ress. If you need to use a specific multicast address, click Sp ecif y t h e
mu lt icast ad d ress man u ally, enter a multicast address into the text box, and click Apply for changes to take effect.
Note
IPV6 is not supported for Cluster Suite in Red Hat Enterprise Linux 5.
If you do not specify a multicast address, the Red Hat Cluster software (specifically, cman, the
Cluster Manager) creates one. It forms the upper 16 bits of the multicast address with 239.192
and forms the lower 16 bits based on the cluster ID.
Note
The cluster ID is a unique identifier that cman generates for each cluster. To view the cluster ID, run the cman_tool status command on a cluster node.
If you do specify a multicast address, you should use the 239.192.x.x series that cman uses.
Otherwise, using a multicast address outside that range may cause unpredictable results. For example, using 224.0.0.x (which is "All hosts on the network") may not be routed correctly, or even routed at all by some hardware.
Note
If you specify a multicast address, make sure that you check the configuration of routers that cluster packets pass through. Some routers may take a long time to learn addresses, seriously impacting cluster performance.
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Red Hat Ent erprise Linux 5 Clust er Administ rat ion
4. Q u o ru m Part it io n tab — This tab provides an interface for configuring these Q u o ru m
Part it io n Co n f ig u rat io n parameters: Do n o t u se a Q u o ru m Part it io n , Use a Q u o ru m
Part it io n , In t erval, Vo t es, T KO , Min imu m Sco re, Device, Lab el, and Heu rist ics. The
Do n o t u se a Q u o ru m Part it io n parameter is enabled by default. Table 3.1, “ Quorum-Disk
Parameters” describes the parameters. If you need to use a quorum disk, click Use a
Q u o ru m Part it io n , enter quorum disk parameters, click Apply, and restart the cluster for the changes to take effect.
Important
Quorum-disk parameters and heuristics depend on the site environment and the special requirements needed. To understand the use of quorum-disk parameters and heuristics, refer to the qdisk(5) man page. If you require assistance understanding and using quorum disk, contact an authorized Red Hat support representative.
Note
Clicking Ap p ly on the Q u o ru m Part it io n tab propagates changes to the cluster configuration file ( /etc/cluster/cluster.conf) in each cluster node. However, for
the quorum disk to operate, you must restart the cluster (refer to Section 4.1, “ Starting,
Stopping, and Deleting Clusters” ).
T ab le 3.1. Q u o ru m- Disk Paramet ers
Paramet er
Do n o t u se a
Q u o ru m Part it io n
Use a Q u o ru m
Part it io n
In t erval
Vo t es
T KO
Min imu m Sco re
Device
Lab el
Descrip t io n
Disables quorum partition. Disables quorum-disk parameters in the
Q u o ru m Part it io n tab.
Enables quorum partition. Enables quorum-disk parameters in the
Q u o ru m Part it io n tab.
The frequency of read/write cycles, in seconds.
The number of votes the quorum daemon advertises to CMAN when it has a high enough score.
The number of cycles a node must miss to be declared dead.
The minimum score for a node to be considered "alive". If omitted or set to
0, the default function, floor((n+1)/2), is used, where n is the sum of the heuristics scores. The Min imu m Sco re value must never exceed the sum of the heuristic scores; otherwise, the quorum disk cannot be available.
The storage device the quorum daemon uses. The device must be the same on all nodes.
Specifies the quorum disk label created by the mkqdisk utility. If this field contains an entry, the label overrides the Device field. If this field is used, the quorum daemon reads /proc/partitions and checks for qdisk signatures on every block device found, comparing the label against the specified label. This is useful in configurations where the quorum device name differs among nodes.
38
Paramet er
Heu rist ics
Chapt er 3. Configuring Red Hat Clust er Wit h Conga
Descrip t io n
Pat h t o Pro g ram — The program used to determine if this heuristic is alive. This can be anything that can be executed by /bin/sh -c. A return value of 0 indicates success; anything else indicates failure. This field is required.
In t erval — The frequency (in seconds) at which the heuristic is polled.
The default interval for every heuristic is 2 seconds.
Sco re — The weight of this heuristic. Be careful when determining scores for heuristics. The default score for each heuristic is 1.
Ap p ly Propagates the changes to the cluster configuration file
(/etc/cluster/cluster.conf) in each cluster node.
3.5. Configuring Fence Devices
Configuring fence devices consists of creating, modifying, and deleting fence devices. Creating a fence device consists of selecting a fence device type and entering parameters for that fence device
(for example, name, IP address, login, and password). Modifying a fence device consists of selecting an existing fence device and changing parameters for that fence device. Deleting a fence device consists of selecting an existing fence device and deleting it.
Note
If you are creating a new cluster, you can create fence devices when you configure cluster
nodes. Refer to Section 3.6, “ Configuring Cluster Members” .
With Co n g a you can create shared and non-shared fence devices. For information on supported
fence devices and their parameters, refer to Appendix B, Fence Device Parameters .
This section provides procedures for the following tasks:
Creating shared fence devices — Refer to Section 3.5.1, “ Creating a Shared Fence Device” . The
procedures apply only to creating shared fence devices. You can create non-shared (and shared)
fence devices while configuring nodes (refer to Section 3.6, “ Configuring Cluster Members” ).
Modifying or deleting fence devices — Refer to Section 3.5.2, “ Modifying or Deleting a Fence
Device” . The procedures apply to both shared and non-shared fence devices.
The starting point of each procedure is at the cluster-specific page that you navigate to from Choose
a cluster to administer displayed on the clu st er tab.
3.5.1. Creat ing a Shared Fence Device
To create a shared fence device, follow these steps:
39
Red Hat Ent erprise Linux 5 Clust er Administ rat ion
1. At the detailed menu for the cluster (below the clu st ers menu), click Sh ared Fen ce
Devices. Clicking Sh ared Fen ce Devices causes the display of the fence devices for a cluster and causes the display of menu items for fence device configuration: Ad d a Fen ce
Device and Co n f ig u re a Fen ce Device.
Note
If this is an initial cluster configuration, no fence devices have been created, and therefore none are displayed.
2. Click Ad d a Fen ce Device. Clicking Ad d a Fen ce Device causes the Add a Sharable
Fence Device page to be displayed (refer to
Figure 3.1, “ Fence Device Configuration” ).
4 0
Fig u re 3.1. Fen ce Device Co n f ig u rat io n
3. At the Add a Sharable Fence Device page, click the drop-down box under Fen cin g
T yp e and select the type of fence device to configure.
Chapt er 3. Configuring Red Hat Clust er Wit h Conga
4. Specify the information in the Fencing Type dialog box according to the type of fence device. Refer to
Appendix B, Fence Device Parameters for more information about fence device
parameters.
5. Click Add this shared fence device.
Clicking Add this shared fence device causes a progress page to be displayed temporarily. After the fence device has been added, the detailed cluster properties menu is updated with the fence device under Co n f ig u re a Fen ce Device.
3.5.2. Modifying or Delet ing a Fence Device
To modify or delete a fence device, follow these steps:
1. At the detailed menu for the cluster (below the clu st ers menu), click Sh ared Fen ce
Devices. Clicking Sh ared Fen ce Devices causes the display of the fence devices for a cluster and causes the display of menu items for fence device configuration: Ad d a Fen ce
Device and Co n f ig u re a Fen ce Device.
2. Click Co n f ig u re a Fen ce Device. Clicking Co n f ig u re a Fen ce Device causes the display of a list of fence devices under Co n f ig u re a Fen ce Device.
3. Click a fence device in the list. Clicking a fence device in the list causes the display of a
Fence Device Form page for the fence device selected from the list.
4. Either modify or delete the fence device as follows:
To modify the fence device, enter changes to the parameters displayed. Refer to
Appendix B, Fence Device Parameters for more information about fence device parameters.
Click Update this fence device and wait for the configuration to be updated.
To delete the fence device, click Delete this fence device and wait for the configuration to be updated.
Note
You can create shared fence devices on the node configuration page, also.
However, you can only modify or delete a shared fence device via Sh ared Fen ce
Devices at the detailed menu for the cluster (below the clu st ers menu).
3.6. Configuring Clust er Members
Configuring cluster members consists of initially configuring nodes in a newly configured cluster, adding members, and deleting members. The following sections provide procedures for initial configuration of nodes, adding nodes, and deleting nodes:
Section 3.6.1, “ Initially Configuring Members”
Section 3.6.2, “ Adding a Member to a Running Cluster”
Section 3.6.3, “ Deleting a Member from a Cluster”
3.6.1. Init ially Configuring Members
4 1
Red Hat Ent erprise Linux 5 Clust er Administ rat ion
Creating a cluster consists of selecting a set of nodes (or members) to be part of the cluster. Once you have completed the initial step of creating a cluster and creating fence devices, you need to configure cluster nodes. To initially configure cluster nodes after creating a new cluster, follow the steps in this section. The starting point of the procedure is at the cluster-specific page that you navigate to from Choose a cluster to administer displayed on the clu st er tab.
1. At the detailed menu for the cluster (below the clu st ers menu), click No d es. Clicking No d es causes the display of an Ad d a No d e element and a Co n f ig u re element with a list of the nodes already configured in the cluster.
2. Click a link for a node at either the list in the center of the page or in the list in the detailed menu under the clu st ers menu. Clicking a link for a node causes a page to be displayed for that link showing how that node is configured.
3. At the bottom of the page, under Main Fen cin g Met h o d , click Add a fence device to
this level.
4. Select a fence device and provide parameters for the fence device (for example port number).
Note
You can choose from an existing fence device or create a new fence device.
5. Click Update main fence properties and wait for the change to take effect.
3.6.2. Adding a Member t o a Running Clust er
To add a member to a running cluster, follow the steps in this section. The starting point of the procedure is at the cluster-specific page that you navigate to from Choose a cluster to
administer displayed on the clu st er tab.
1. At the detailed menu for the cluster (below the clu st ers menu), click No d es. Clicking No d es causes the display of an Ad d a No d e element and a Co n f ig u re element with a list of the nodes already configured in the cluster. (In addition, a list of the cluster nodes is displayed in the center of the page.)
2. Click Ad d a No d e. Clicking Ad d a No d e causes the display of the Add a node to
cluster name page.
3. At that page, enter the node name in the No d e Ho st n ame text box; enter the root password in the Ro o t Passwo rd text box. Check the En ab le Sh ared St o rag e Su p p o rt checkbox if clustered storage is required. If you want to add more nodes, click Add another entry and enter node name and password for the each additional node.
4. Click Submit. Clicking Submit causes the following actions: a. Cluster software packages to be downloaded onto the added node.
b. Cluster software to be installed (or verification that the appropriate software packages are installed) onto the added node.
c. Cluster configuration file to be updated and propagated to each node in the cluster — including the added node.
d. Joining the added node to cluster.
4 2
Chapt er 3. Configuring Red Hat Clust er Wit h Conga
A progress page shows the progress of those actions for each added node.
5. When the process of adding a node is complete, a page is displayed providing a configuration interface for the cluster.
6. At the detailed menu for the cluster (below the clu st ers menu), click No d es. Clicking No d es causes the following displays:
A list of cluster nodes in the center of the page
The Ad d a No d e element and the Co n f ig u re element with a list of the nodes configured in the cluster at the detailed menu for the cluster (below the clu st ers menu)
7. Click the link for an added node at either the list in the center of the page or in the list in the detailed menu under the clu st ers menu. Clicking the link for the added node causes a page to be displayed for that link showing how that node is configured.
8. At the bottom of the page, under Main Fen cin g Met h o d , click Add a fence device to
this level.
9. Select a fence device and provide parameters for the fence device (for example port number).
Note
You can choose from an existing fence device or create a new fence device.
10. Click Update main fence properties and wait for the change to take effect.
3.6.3. Delet ing a Member from a Clust er
To delete a member from an existing cluster that is currently in operation, follow the steps in this section. The starting point of the procedure is at the Choose a cluster to administer page
(displayed on the clu st er tab).
1. Click the link of the node to be deleted. Clicking the link of the node to be deleted causes a page to be displayed for that link showing how that node is configured.
Note
To allow services running on a node to fail over when the node is deleted, skip the next step.
2. Disable or relocate each service that is running on the node to be deleted:
Note
Repeat this step for each service that needs to be disabled or started on another node.
a. Under Services o n t h is No d e, click the link for a service. Clicking that link cause a configuration page for that service to be displayed.
4 3
Red Hat Ent erprise Linux 5 Clust er Administ rat ion b. On that page, at the Ch o o se a t askdrop-down box, choose to either disable the service are start it on another node and click Go.
c. Upon confirmation that the service has been disabled or started on another node, click the clu st er tab. Clicking the clu st er tab causes the Choose a cluster to
administer page to be displayed.
d. At the Choose a cluster to administer page, click the link of the node to be deleted. Clicking the link of the node to be deleted causes a page to be displayed for that link showing how that node is configured.
3. On that page, at the Ch o o se a t askdrop-down box, choose Delet e t h is n o d e and click
Go. When the node is deleted, a page is displayed that lists the nodes in the cluster. Check the list to make sure that the node has been deleted.
3.7. Configuring a Failover Domain
A failover domain is a named subset of cluster nodes that are eligible to run a cluster service in the event of a node failure. A failover domain can have the following characteristics:
Unrestricted — Allows you to specify that a subset of members are preferred, but that a cluster service assigned to this domain can run on any available member.
Restricted — Allows you to restrict the members that can run a particular cluster service. If none of the members in a restricted failover domain are available, the cluster service cannot be started
(either manually or by the cluster software).
Unordered — When a cluster service is assigned to an unordered failover domain, the member on which the cluster service runs is chosen from the available failover domain members with no priority ordering.
Ordered — Allows you to specify a preference order among the members of a failover domain. The member at the top of the list is the most preferred, followed by the second member in the list, and so on.
Failback — Allows you to specify whether a service in the failover domain should fail back to the node that it was originally running on before that node failed. Configuring this characteristic is useful in circumstances where a node repeatedly fails and is part of an ordered failover domain.
In that circumstance, if a node is the preferred node in a failover domain, it is possible for a service to fail over and fail back repeatedly between the preferred node and another node, causing severe impact on performance.
Note
The failback characteristic is applicable only if ordered failover is configured.
Note
Changing a failover domain configuration has no effect on currently running services.
4 4
Chapt er 3. Configuring Red Hat Clust er Wit h Conga
Note
Failover domains are not required for operation.
By default, failover domains are unrestricted and unordered.
In a cluster with several members, using a restricted failover domain can minimize the work to set up the cluster to run a cluster service (such as httpd), which requires you to set up the configuration identically on all members that run the cluster service). Instead of setting up the entire cluster to run the cluster service, you must set up only the members in the restricted failover domain that you associate with the cluster service.
Note
To configure a preferred member, you can create an unrestricted failover domain comprising only one cluster member. Doing that causes a cluster service to run on that cluster member primarily (the preferred member), but allows the cluster service to fail over to any of the other members.
The following sections describe adding a failover domain and modifying a failover domain:
Section 3.7.1, “ Adding a Failover Domain”
Section 3.7.2, “ Modifying a Failover Domain”
3.7.1. Adding a Failover Domain
To add a failover domain, follow the steps in this section. The starting point of the procedure is at the cluster-specific page that you navigate to from Choose a cluster to administer displayed on the clu st er tab.
1. At the detailed menu for the cluster (below the clu st ers menu), click Failo ver Do main s.
Clicking Failo ver Do main s causes the display of failover domains with related services and the display of menu items for failover domains: Ad d a Failo ver Do main and Co n f ig u re a
Failo ver Do main .
2. Click Ad d a Failo ver Do main . Clicking Ad d a Failo ver Do main causes the display of the
Add a Failover Domain page.
3. At the Add a Failover Domain page, specify a failover domain name at the Failo ver
Do main Name text box.
Note
The name should be descriptive enough to distinguish its purpose relative to other names used in your cluster.
4. To enable setting failover priority of the members in the failover domain, click the Prio rit iz ed checkbox. With Prio rit iz ed checked, you can set the priority value, Prio rit y, for each node selected as members of the failover domain.
4 5
Red Hat Ent erprise Linux 5 Clust er Administ rat ion
5. To restrict failover to members in this failover domain, click the checkbox next to Rest rict
f ailo ver t o t h is d o main ' s memb ers. With Rest rict f ailo ver t o t h is d o main ' s
memb ers checked, services assigned to this failover domain fail over only to nodes in this failover domain.
6. To specify that a node does not fail back in this failover domain, click the checkbox next to
Do n o t f ail b ack services in t h is d o main . With Do n o t f ail b ack services in t h is
d o main checked, if a service fails over from a preferred node, the service does not fail back to the original node once it has recovered.
7. Configure members for this failover domain. Under Failo ver d o main memb ersh ip , click the
Memb er checkbox for each node that is to be a member of the failover domain. If
Prio rit iz ed is checked, set the priority in the Prio rit y text box for each member of the failover domain.
8. Click Submit. Clicking Submit causes a progress page to be displayed followed by the display of the Failover Domain Form page. That page displays the added resource and includes the failover domain in the cluster menu to the left under Do main .
9. To make additional changes to the failover domain, continue modifications at the Failover
Domain Form page and click Submit when you are done.
3.7.2. Modifying a Failover Domain
To modify a failover domain, follow the steps in this section. The starting point of the procedure is at the cluster-specific page that you navigate to from Choose a cluster to administer displayed on the clu st er tab.
1. At the detailed menu for the cluster (below the clu st ers menu), click Failo ver Do main s.
Clicking Failo ver Do main s causes the display of failover domains with related services and the display of menu items for failover domains: Ad d a Failo ver Do main and Co n f ig u re a
Failo ver Do main .
2. Click Co n f ig u re a Failo ver Do main . Clicking Co n f ig u re a Failo ver Do main causes the display of failover domains under Co n f ig u re a Failo ver Do main at the detailed menu for the cluster (below the clu st ers menu).
3. At the detailed menu for the cluster (below the clu st ers menu), click the failover domain to modify. Clicking the failover domain causes the display of the Failover Domain Form page. At the Failover Domain Form page, you can modify the failover domain name, prioritize failover, restrict failover to this domain, and modify failover domain membership.
4. Modifying failover name — To change the failover domain name, modify the text at the
Failo ver Do main Name text box.
Note
The name should be descriptive enough to distinguish its purpose relative to other names used in your cluster.
5. Failover priority — To enable or disable prioritized failover in this failover domain, click the
Prio rit iz ed checkbox. With Prio rit iz ed checked, you can set the priority value, Prio rit y, for each node selected as members of the failover domain. With Prio rit iz ed not checked, setting priority levels is disabled for this failover domain.
4 6
Chapt er 3. Configuring Red Hat Clust er Wit h Conga
6. Restricted failover — To enable or disable restricted failover for members in this failover domain, click the checkbox next to Rest rict f ailo ver t o t h is d o main ' s memb ers. With
Rest rict f ailo ver t o t h is d o main ' s memb ers checked, services assigned to this failover domain fail over only to nodes in this failover domain. With Rest rict f ailo ver t o t h is
d o main ' s memb ers not checked, services assigned to this failover domain can fail over to nodes outside this failover domain.
7. Failback — To enable or disable failback in a failover domain, click the checkbox next to Do
n o t f ail b ack services in t h is d o main . With Do n o t f ail b ack services in t h is d o main checked, if a service fails over from a preferred node, the service does not fail back to the original node once it has recovered.
8. Modifying failover domain membership — Under Failo ver d o main memb ersh ip , click the
Memb ercheckbox for each node that is to be a member of the failover domain. A checked box for a node means that the node is a member of the failover domain. If Prio rit iz ed is checked, you can adjust the priority in the Prio rit y text box for each member of the failover domain.
9. Click Submit. Clicking Submit causes a progress page to be displayed followed by the display of the Failover Domain Form page. That page displays the added resource and includes the failover domain in the cluster menu to the left under Do main .
10. To make additional changes to the failover domain, continue modifications at the Failover
Domain Form page and click Submit when you are done.
3.8. Adding Clust er Resources
To add a cluster resource, follow the steps in this section. The starting point of the procedure is at the cluster-specific page that you navigate to from Choose a cluster to administer displayed on the clu st er tab.
1. At the detailed menu for the cluster (below the clu st ers menu), click Reso u rces. Clicking
Reso u rces causes the display of resources in the center of the page and causes the display of menu items for resource configuration: Ad d a Reso u rce and Co n f ig u re a Reso u rce.
2. Click Ad d a Reso u rce. Clicking Ad d a Reso u rce causes the Add a Resource page to be displayed.
3. At the Add a Resource page, click the drop-down box under Select a Reso u rce T yp e
and select the type of resource to configure. Appendix C, HA Resource Parameters
describes resource parameters.
4. Click Submit. Clicking Submit causes a progress page to be displayed followed by the display of Resources forcluster name page. That page displays the added resource
(and other resources).
3.9. Adding a Clust er Service t o t he Clust er
To add a cluster service to the cluster, follow the steps in this section. The starting point of the procedure is at the cluster-specific page that you navigate to from Choose a cluster to
administer displayed on the clu st er tab.
4 7
Red Hat Ent erprise Linux 5 Clust er Administ rat ion
1. At the detailed menu for the cluster (below the clu st ers menu), click Services. Clicking
Services causes the display of services in the center of the page and causes the display of menu items for services configuration: Ad d a Service, Ad d a Virt u al Mach in e Service, and Co n f ig u re a Service.
2. To configure any service other than a virtual machine service, Click Ad d a Service. Clicking
Ad d a Service causes the Add a Service page to be displayed.
3. On the Add a Service page, at the Service n ame text box, type the name of the service.
Note
Use a descriptive name that clearly distinguishes the service from other services in the cluster.
4. Below the Service n ame text box, enter the following parameters for this service.
Au t o mat ically st art t h is service — When the checkbox is checked, the service is started automatically when a cluster is started and running. If the checkbox is not checked, the service must be started manually any time the cluster comes up from the stopped state.
En ab le NFS lo ck wo rkaro u n d s — Setting this option will release NFS locks on a file system in a soft attempt to unmount a file system, which may be necessary if your filesystem is exported via NFS and occasionally fails to unmount (either during shutdown or service relocation). You can also enable NFS daemon and lock workarounds for individual file system resources, which will result in a hard attempt to unmount a file
system, as described in the table of file system resource parameters, Table C.3, “ File
System” , and the table of GFS resource parameters, Table C.4, “ GFS” .
Ru n exclu sive — If enabled, this service (resource group) can only be relocated to run on another node exclusively; that is, to run on a node that has no other services running on it. If no nodes are available for a service to run exclusively, the service is not restarted after a failure. Additionally, other services do not automatically relocate to a node running this service as Run exclusive. You can override this option by manual start or relocate operations.
Failo ver Do main — List of cluster members to try in the event that a service fails. For
information on configuring a failover domain with Conga, refer to Section 3.7,
“ Configuring a Failover Domain” .
Reco very p o licy Provides the following options:
Disab le — Disables the resource group if any component fails.
Relo cat e — Tries to restart service in another node; that is, it does not try to restart in the current node.
Rest art — Tries to restart failed parts of this service locally (in the current node) before trying to relocate (default) to service to another node.
Rest art - Disab le — (Red Hat Enterprise Linux release 5.6 and later) The service will be restarted in place if it fails. However, if restarting the service fails the service will be disabled instead of being moved to another host in the cluster.
In addition, you can specify the Maximu m n u mb er o f rest art f ailu res b ef o re
relo cat in g and the Len g t h o f t ime in seco n d s af t er wh ich t o f o rg et a rest art .
4 8
Chapt er 3. Configuring Red Hat Clust er Wit h Conga
5. Add a resource to the service; click Add a resource to this service. Clicking Add a
resource to this service causes the display of two drop-down boxes: Ad d a n ew
lo cal reso u rce and Use an exist in g g lo b al reso u rce. Adding a new local resource adds a resource that is available only to this service. The process of adding a local resource
is the same as adding a global resource described in Section 3.8, “ Adding Cluster
6. At the drop-down box of either Ad d a n ew lo cal reso u rce or Use an exist in g g lo b al
reso u rce, select the resource to add and configure it according to the options presented.
(The options are the same as described in Section 3.8, “ Adding Cluster Resources” .)
Note
If you are adding a Samba-service resource, connect a Samba-service resource directly to the service, not to a resource within a service.
7. If you want to add resources to that resource, click Add a child. Clicking Add a child causes the display of additional options to local and global resources. You can continue adding children resources to the resource to suit your requirements. To view children resources, click the triangle icon to the left of Sh o w Ch ild ren .
8. When you have completed adding resources to the service, and have completed adding children resources to resources, click Submit. Clicking Submit causes a progress page to be displayed followed by a page displaying the added service (and other services).
Note
To verify the existence of the IP service resource used in a cluster service, you must use the
/sbin/ip addr list command on a cluster node. The following output shows the
/sbin/ip addr list command executed on a node running a cluster service:
1: lo: <LOOPBACK,UP> mtu 16436 qdisc noqueue
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP> mtu 1356 qdisc pfifo_fast qlen 1000
link/ether 00:05:5d:9a:d8:91 brd ff:ff:ff:ff:ff:ff
inet 10.11.4.31/22 brd 10.11.7.255 scope global eth0
inet6 fe80::205:5dff:fe9a:d891/64 scope link
inet 10.11.4.240/22 scope global secondary eth0
valid_lft forever preferred_lft forever
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Red Hat Ent erprise Linux 5 Clust er Administ rat ion
Configuring a Virtual Machine Service
To configure a virtual machine service, after clicking Services you can click Ad d a Virt u al
Mach in e Service. Enter the virtual machine resource parameters. For a description of the virtual machine parameters, refer to
Table C.23, “ Virtual Machine”
. When you have completed adding the virtual machine resource parameters, click Create Virtual Machine
Service.
3.10. Configuring Clust er St orage
To configure storage for a cluster, click the st o rag e tab. Clicking that tab causes the display of the
Welcome to Storage Configuration Interface page.
The st o rag e tab allows you to monitor and configure storage on remote systems. It provides a means for configuring disk partitions, logical volumes (clustered and single system use), file system parameters, and mount points. The st o rag e tab provides an interface for setting up shared storage for clusters and offers GFS and other file systems as file system options. When a you select the
st o rag e tab, the Welcome to Storage Configuration Interface page shows a list of systems available to the you in a navigation table to the left. A small form allows you to choose a storage unit size to suit your preference. That choice is persisted and can be changed at any time by returning to this page. In addition, you can change the unit type on specific configuration forms throughout the storage user interface. This general choice allows you to avoid difficult decimal representations of storage size (for example, if you know that most of your storage is measured in gigabytes, terabytes, or other more familiar representations).
Additionally, the Welcome to Storage Configuration Interface page lists systems that you are authorized to access, but currently are unable to administer because of a problem. Examples of problems:
A computer is unreachable via the network.
A computer has been re-imaged and the lu ci server admin must re-authenticate with the ricci agent on the computer.
A reason for the trouble is displayed if the storage user interface can determine it.
Only those computers that the user is privileged to administer is shown in the main navigation table.
If you have no permissions on any computers, a message is displayed.
After you select a computer to administer, a general properties page is displayed for the computer.
This page is divided into three sections:
Hard Drives
Part it io n s
Vo lu me G ro u p s
Each section is set up as an expandable tree, with links to property sheets for specific devices, partitions, and storage entities.
Configure the storage for your cluster to suit your cluster requirements. If you are configuring Red Hat
GFS, configure clustered logical volumes first, using CLVM. For more information about CLVM and
GFS refer to Red Hat documentation for those products.
50
Chapt er 3. Configuring Red Hat Clust er Wit h Conga
Note
Shared storage for use in Red Hat Cluster Suite requires that you be running the cluster logical volume manager daemon ( clvmd) or the High Availability Logical Volume Management agents (HA-LVM). If you are not able to use either the clvmd daemon or HA-LVM for operational reasons or because you do not have the correct entitlements, you must not use single-instance LVM on the shared disk as this may result in data corruption. If you have any concerns please contact your Red Hat service representative.
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Red Hat Ent erprise Linux 5 Clust er Administ rat ion
Chapter 4. Managing Red Hat Cluster With Conga
This chapter describes various administrative tasks for managing a Red Hat Cluster and consists of the following sections:
Section 4.1, “ Starting, Stopping, and Deleting Clusters”
Section 4.2, “ Managing Cluster Nodes”
Section 4.3, “ Managing High-Availability Services”
Section 4.4, “ Backing Up and Restoring the luci Configuration”
Section 4.5, “ Diagnosing and Correcting Problems in a Cluster”
4 .1. St art ing, St opping, and Delet ing Clust ers
You can perform the following cluster-management functions through the lu ci server component of
Co n g a:
Restart a cluster.
Start a cluster.
Stop a cluster.
Delete a cluster.
To perform one of the functions in the preceding list, follow the steps in this section. The starting point of the procedure is at the clu st er tab (at the Choose a cluster to administer page).
1. At the right of the Clu st er Name for each cluster listed on the Choose a cluster to
administer page is a drop-down box. By default, the drop-down box is set to Rest art t h is
clu st er. Clicking the drop-down box box reveals all the selections available: Rest art t h is
clu st er, St o p t h is clu st er/St art t h is clu st er, and Delet e t h is clu st er. The actions of each function are summarized as follows:
Rest art t h is clu st er — Selecting this action causes the cluster to be restarted. You can select this action for any state the cluster is in.
St o p t h is clu st er/St art t h is clu st er — St o p t h is clu st er is available when a cluster is running. St art t h is clu st er is available when a cluster is stopped.
Selecting St o p t h is clu st er shuts down cluster software in all cluster nodes.
Selecting St art t h is clu st er starts cluster software.
Delet e t h is clu st er — Selecting this action halts a running cluster, disables cluster software from starting automatically, and removes the cluster configuration file from each node. You can select this action for any state the cluster is in. Deleting a cluster frees each node in the cluster for use in another cluster.
2. Select one of the functions and click Go.
3. Clicking Go causes a progress page to be displayed. When the action is complete, a page is displayed showing either of the following pages according to the action selected:
52
Chapt er 4 . Managing Red Hat Clust er Wit h Conga
For Rest art t h is clu st er and St o p t h is clu st er/St art t h is clu st er — Displays a page with the list of nodes for the cluster.
For Delet e t h is clu st er — Displays the Choose a cluster to administer page in the clu st er tab, showing a list of clusters.
4 .2. Managing Clust er Nodes
You can perform the following node-management functions through the lu ci server component of
Co n g a:
Make a node leave or join a cluster.
Fence a node.
Reboot a node.
Delete a node.
To perform one the functions in the preceding list, follow the steps in this section. The starting point of the procedure is at the cluster-specific page that you navigate to from Choose a cluster to
administer displayed on the clu st er tab.
1. At the detailed menu for the cluster (below the clu st ers menu), click No d es. Clicking No d es causes the display of nodes in the center of the page and causes the display of an Ad d a
No d e element and a Co n f ig u re element with a list of the nodes already configured in the cluster.
2. At the right of each node listed on the page displayed from the preceding step, click the
Ch o o se a t ask drop-down box. Clicking Ch o o se a t ask drop-down box reveals the following selections: Have n o d e leave clu st er/Have n o d e jo in clu st er, Fen ce t h is
n o d e, Reb o o t t h is n o d e, and Delet e. The actions of each function are summarized as follows:
Have n o d e leave clu st er/Have n o d e jo in clu st er — Have n o d e leave clu st er is available when a node has joined of a cluster. Have n o d e jo in clu st er is available when a node has left a cluster.
Selecting Have n o d e leave clu st er shuts down cluster software and makes the node leave the cluster. Making a node leave a cluster prevents the node from automatically joining the cluster when it is rebooted.
Selecting Have n o d e jo in clu st er starts cluster software and makes the node join the cluster. Making a node join a cluster allows the node to automatically join the cluster when it is rebooted.
Fen ce t h is n o d e — Selecting this action causes the node to be fenced according to how the node is configured to be fenced.
Reb o o t t h is n o d e — Selecting this action causes the node to be rebooted.
Delet e — Selecting this action causes the node to be deleted from the cluster configuration. It also stops all cluster services on the node, and deletes the
cluster.conf file from /etc/cluster/.
3. Select one of the functions and click Go.
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Red Hat Ent erprise Linux 5 Clust er Administ rat ion
4. Clicking Go causes a progress page to be displayed. When the action is complete, a page is displayed showing the list of nodes for the cluster.
4 .3. Managing High-Availabilit y Services
You can perform the following management functions for high-availability services through the lu ci server component of Co n g a:
Configure a service.
Stop or start a service.
Restart a service.
Delete a service
To perform one the functions in the preceding list, follow the steps in this section. The starting point of the procedure is at the cluster-specific page that you navigate to from Choose a cluster to
administer displayed on the clu st er tab.
1. At the detailed menu for the cluster (below the clu st ers menu), click Services. Clicking
Services causes the display of services for the cluster in the center of the page.
2. At the right of each service listed on the page, click the Ch o o se a t ask drop-down box.
Clicking Ch o o se a t ask drop-down box reveals the following selections depending on if the service is running:
If service is running — Co n f ig u re t h is service, Rest art t h is service, and St o p t h is
service.
If service is not running — Co n f ig u re t h is service, St art t h is service, and Delet e
t h is service.
The actions of each function are summarized as follows:
Co n f ig u re t h is service — Co n f ig u re t h is service is available when the service is running or not running. Selecting Co n f ig u re t h is service causes the services configuration page for the service to be displayed. On that page, you can change the configuration of the service. For example, you can add a resource to the service. (For
more information about adding resources and services, refer to Section 3.8, “ Adding
Cluster Resources” and Section 3.9, “ Adding a Cluster Service to the Cluster” .) In
addition, a drop-down box on the page provides other functions depending on if the service is running.
When a service is running, the drop-down box provides the following functions: restarting, disabling, and relocating the service.
When a service is not running, the drop-down box on the configuration page provides the following functions: enabling and deleting the service.
If you are making configuration changes, save the changes by clicking Save. Clicking
Save causes a progress page to be displayed. When the change is complete, another page is displayed showing a list of services for the cluster.
If you have selected one of the functions in the drop-down box on the configuration page, click Go. Clicking Go causes a progress page to be displayed. When the change is complete, another page is displayed showing a list of services for the cluster.
54
Chapt er 4 . Managing Red Hat Clust er Wit h Conga
Rest art t h is service and St o p t h is service — These selections are available when the service is running. Select either function and click Go to make the change take effect.
Clicking Go causes a progress page to be displayed. When the change is complete, another page is displayed showing a list of services for the cluster.
St art t h is service and Delet e t h is service — These selections are available when the service is not running. Select either function and click Go to make the change take effect.
Clicking Go causes a progress page to be displayed. When the change is complete, another page is displayed showing a list of services for the cluster.
4 .4 . Backing Up and Rest oring t he luci Configurat ion
You can use the following procedure to make a backup of the lu ci database, which is stored in the
/var/lib/luci/var/Data.fs file. This is not the cluster configuration itself, which is stored in the
cluster.conf file. Instead, it contains the list of users and clusters and related properties that lu ci maintains.
1. Execute service luci stop.
2. Execute luci_admin backup [backup_xml_file_path].
Specifying the backup_xml_file_path is optional. If you do not specify a file path, the backup file will be written to /var/lib/luci/var/luci_backup.xml.
3. Execute service luci start.
Use the following procedure to restore a lu ci database.
1. Execute service luci stop.
2. Execute luci_admin restore -r backup_xml_file_path.
If you do not specify a backup path argument, the command uses
/var/lib/luci/var/luci_backup.xml.
Specifying the -r option indicates that you will replace all configuration with the configuration specified in the backup file. If you do not specify this option, the default behavior (which you can also specify with the -u) is to merge any additional configuration information from the XML backup into the current database.
3. Execute service luci start.
4 .5. Diagnosing and Correct ing Problems in a Clust er
For information about diagnosing and correcting problems in a cluster, contact an authorized Red
Hat support representative.
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Red Hat Ent erprise Linux 5 Clust er Administ rat ion
Chapter 5. Configuring Red Hat Cluster With system-configcluster
This chapter describes how to configure Red Hat Cluster software using system-config-cluster, and consists of the following sections:
Section 5.1, “ Configuration Tasks”
Section 5.2, “ Starting the Clu st er Co n f ig u rat io n T o o l”
Section 5.3, “ Configuring Cluster Properties”
Section 5.4, “ Configuring Fence Devices”
Section 5.5, “ Adding and Deleting Members”
Section 5.6, “ Configuring a Failover Domain”
Section 5.7, “ Adding Cluster Resources”
Section 5.8, “ Adding a Cluster Service to the Cluster”
Section 5.9, “ Propagating The Configuration File: New Cluster”
Section 5.10, “ Starting the Cluster Software”
Note
While system-config-cluster provides several convenient tools for configuring and managing a Red Hat Cluster, the newer, more comprehensive tool, Co n g a, provides more convenience and flexibility than system-config-cluster. You may want to consider using
Co n g a instead (refer to Chapter 3, Configuring Red Hat Cluster With Conga
Managing Red Hat Cluster With Conga ).
5.1. Configurat ion T asks
Configuring Red Hat Cluster software with system-config-cluster consists of the following steps:
1. Starting the Clu st er Co n f ig u rat io n T o o l, system-config-cluster. Refer to
Section 5.2, “ Starting the Clu st er Co n f ig u rat io n T o o l”
.
2. Configuring cluster properties. Refer to Section 5.3, “ Configuring Cluster Properties” .
3. Creating fence devices. Refer to Section 5.4, “ Configuring Fence Devices”
.
4. Creating cluster members. Refer to Section 5.5, “ Adding and Deleting Members” .
5. Creating failover domains. Refer to
Section 5.6, “ Configuring a Failover Domain”
.
6. Creating resources. Refer to Section 5.7, “ Adding Cluster Resources”
.
7. Creating cluster services.
Refer to Section 5.8, “ Adding a Cluster Service to the Cluster” .
56
Chapt er 5. Configuring Red Hat Clust er Wit h syst em- config- clust er
8. Propagating the configuration file to the other nodes in the cluster.
Refer to Section 5.9, “ Propagating The Configuration File: New Cluster”
.
9. Starting the cluster software. Refer to Section 5.10, “ Starting the Cluster Software”
.
5.2. St art ing t he Clust er Configurat ion T ool
You can start the Clu st er Co n f ig u rat io n T o o l by logging in to a cluster node as root with the ssh
-Y command and issuing the system-config-cluster command. For example, to start the
Clu st er Co n f ig u rat io n T o o l on cluster node nano-01, do the following:
1. Log in to a cluster node and run system-config-cluster. For example:
$ ssh -Y root@nano-01
.
.
.
# system-config-cluster
2. If this is the first time you have started the Clu st er Co n f ig u rat io n T o o l, the program prompts you to either open an existing configuration or create a new one. Click Create New
Configuration to start a new configuration file (refer to Figure 5.1, “ Starting a New
Fig u re 5.1. St art in g a New Co n f ig u rat io n File
Note
The Clu st er Man ag emen t tab for the Red Hat Cluster Suite management GUI is available after you save the configuration file with the Clu st er Co n f ig u rat io n T o o l, exit, and restart the Red Hat Cluster Suite management GUI ( system-config-
cluster). (The Clu st er Man ag emen t tab displays the status of the cluster service manager, cluster nodes, and resources, and shows statistics concerning cluster service operation. To manage the cluster system further, choose the Clu st er
Co n f ig u rat io n tab.)
3. Clicking Create New Configuration causes the New Configuration dialog box to be displayed (refer to
Figure 5.2, “ Creating A New Configuration” ). The
New Configuration
57
Red Hat Ent erprise Linux 5 Clust er Administ rat ion dialog box provides a text box for cluster name and the following checkboxes: Cu st o m
Co n f ig u re Mu lt icast and Use a Q u o ru m Disk. In most circumstances you only need to configure the cluster name.
Note
Choose the cluster name carefully. The only way to change the name of a Red Hat cluster is to create a new cluster configuration with the new name.
Cust om Configure Mult icast
Red Hat Cluster software chooses a multicast address for cluster management communication among cluster nodes. If you need to use a specific multicast address, click the Cu st o m Co n f ig u re Mu lt icast checkbox and enter a multicast address in the Ad d ress text boxes.
Note
IPV6 is not supported for Cluster Suite in Red Hat Enterprise Linux 5.
If you do not specify a multicast address, the Red Hat Cluster software (specifically, cman, the
Cluster Manager) creates one. It forms the upper 16 bits of the multicast address with 239.192
and forms the lower 16 bits based on the cluster ID.
Note
The cluster ID is a unique identifier that cman generates for each cluster. To view the cluster ID, run the cman_tool status command on a cluster node.
If you do specify a multicast address, you should use the 239.192.x.x series that cman uses.
Otherwise, using a multicast address outside that range may cause unpredictable results. For example, using 224.0.0.x (which is "All hosts on the network") may not be routed correctly, or even routed at all by some hardware.
Note
If you specify a multicast address, make sure that you check the configuration of routers that cluster packets pass through. Some routers may take a long time to learn addresses, seriously impacting cluster performance.
Use a Quorum Disk
If you need to use a quorum disk, click the Use a Q u o ru m d isk checkbox and enter quorum disk parameters. The following quorum-disk parameters are available in the dialog box if you enable Use a Q u o ru m d isk: In t erval, T KO , Vo t es, Min imu m Sco re, Device, Lab el, and
Q u o ru m Disk Heu rist ic.
Table 5.1, “ Quorum-Disk Parameters”
describes the parameters.
58
Chapt er 5. Configuring Red Hat Clust er Wit h syst em- config- clust er
Important
Quorum-disk parameters and heuristics depend on the site environment and special requirements needed. To understand the use of quorum-disk parameters and heuristics, refer to the qdisk(5) man page. If you require assistance understanding and using quorum disk, contact an authorized Red Hat support representative.
Note
It is probable that configuring a quorum disk requires changing quorum-disk parameters after the initial configuration. The Clu st er Co n f ig u rat io n T o o l
( system-config-cluster) provides only the display of quorum-disk parameters after initial configuration. If you need to configure quorum disk, consider using Co n g a instead; Co n g a allows modification of quorum disk parameters.
Overall:
While system-config-cluster provides several convenient tools for configuring and managing a Red Hat Cluster, the newer, more comprehensive tool, Co n g a, provides more convenience and flexibility than system-config-cluster. You may
want to consider using Co n g a instead (refer to Chapter 3, Configuring Red Hat Cluster
With Conga and Chapter 4, Managing Red Hat Cluster With Conga ).
59
Red Hat Ent erprise Linux 5 Clust er Administ rat ion
60
Fig u re 5.2. Creat in g A New Co n f ig u rat io n
4. When you have completed entering the cluster name and other parameters in the New
Configuration dialog box, click OK. Clicking OK starts the Clu st er Co n f ig u rat io n T o o l,
displaying a graphical representation of the configuration ( Figure 5.3, “ The Cluster
Chapt er 5. Configuring Red Hat Clust er Wit h syst em- config- clust er
Fig u re 5.3. T h e Clu st er Co n f ig u rat io n T o o l
T ab le 5.1. Q u o ru m- Disk Paramet ers
Paramet er Descrip t io n
Use a Q u o ru m Disk Enables quorum disk. Enables quorum-disk parameters in the New
Configuration dialog box.
In t erval
T KO
Vo t es
Min imu m Sco re
Device
The frequency of read/write cycles, in seconds.
The number of cycles a node must miss in order to be declared dead.
The number of votes the quorum daemon advertises to CMAN when it has a high enough score.
The minimum score for a node to be considered "alive". If omitted or set to
0, the default function, floor((n+1)/2), is used, where n is the sum of the heuristics scores. The Min imu m Sco re value must never exceed the sum of the heuristic scores; otherwise, the quorum disk cannot be available.
The storage device the quorum daemon uses. The device must be the same on all nodes.
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Paramet er
Lab el
Q u o ru m Disk
Heu rist ics
Descrip t io n
Specifies the quorum disk label created by the mkqdisk utility. If this field contains an entry, the label overrides the Device field. If this field is used, the quorum daemon reads /proc/partitions and checks for qdisk signatures on every block device found, comparing the label against the specified label. This is useful in configurations where the quorum device name differs among nodes.
Pro g ram — The program used to determine if this heuristic is alive. This can be anything that can be executed by /bin/sh -c. A return value of
0 indicates success; anything else indicates failure. This field is required.
Sco re — The weight of this heuristic. Be careful when determining scores for heuristics. The default score for each heuristic is 1.
In t erval — The frequency (in seconds) at which the heuristic is polled.
The default interval for every heuristic is 2 seconds.
5.3. Configuring Clust er Propert ies
In addition to configuring cluster parameters in the preceding section ( Section 5.2, “ Starting the
(optional), a Co n f ig Versio n (optional), and Fen ce Daemo n Pro p ert ies. To configure cluster properties, follow these steps:
1. At the left frame, click Clu st er.
2. At the bottom of the right frame (labeled Pro p ert ies), click the Edit Cluster Properties button. Clicking that button causes a Cluster Properties dialog box to be displayed.
The Cluster Properties dialog box presents text boxes for Clu st er Alias, Co n f ig
Versio n , and two Fen ce Daemo n Pro p ert ies parameters: Po st - Jo in Delay and Po st -
Fail Delay.
3. (Optional) At the Clu st er Alias text box, specify a cluster alias for the cluster. The default cluster alias is set to the true cluster name provided when the cluster is set up (refer to
Section 5.2, “ Starting the Clu st er Co n f ig u rat io n T o o l”
). The cluster alias should be descriptive enough to distinguish it from other clusters and systems on your network (for example, nfs_cluster or httpd_cluster). The cluster alias cannot exceed 15 characters.
4. (Optional) The Co n f ig Versio n value is set to 1 by default and is automatically incremented each time you save your cluster configuration. However, if you need to set it to another value, you can specify it at the Co n f ig Versio n text box.
5. Specify the Fen ce Daemo n Pro p ert ies parameters: Po st - Jo in Delay and Po st - Fail
Delay.
a. The Po st - Jo in Delay parameter is the number of seconds the fence daemon
( fenced) waits before fencing a node after the node joins the fence domain. The
Po st - Jo in Delay default value is 3. A typical setting for Po st - Jo in Delay is between 20 and 30 seconds, but can vary according to cluster and network performance.
b. The Po st - Fail Delay parameter is the number of seconds the fence daemon
( fenced) waits before fencing a node (a member of the fence domain) after the node has failed.The Po st - Fail Delay default value is 0. Its value may be varied to suit cluster and network performance.
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Chapt er 5. Configuring Red Hat Clust er Wit h syst em- config- clust er
Note
For more information about Po st - Jo in Delay and Po st - Fail Delay, refer to the fenced(8) man page.
6. Save cluster configuration changes by selecting File => Save.
5.4 . Configuring Fence Devices
Configuring fence devices for the cluster consists of selecting one or more fence devices and specifying fence-device-dependent parameters (for example, name, IP address, login, and password).
To configure fence devices, follow these steps:
1. Click Fen ce Devices. At the bottom of the right frame (labeled Pro p ert ies), click the Add a
Fence Device button. Clicking Add a Fence Device causes the Fence Device
Configuration dialog box to be displayed (refer to Figure 5.4, “ Fence Device
Fig u re 5.4 . Fen ce Device Co n f ig u rat io n
2. At the Fence Device Configuration dialog box, click the drop-down box under Ad d a
New Fen ce Device and select the type of fence device to configure.
3. Specify the information in the Fence Device Configuration dialog box according to the
type of fence device. Refer to Appendix B, Fence Device Parameters
for more information about fence device parameters.
4. Click OK.
5. Choose File => Save to save the changes to the cluster configuration.
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5.5. Adding and Delet ing Members
The procedure to add a member to a cluster varies depending on whether the cluster is a newlyconfigured cluster or a cluster that is already configured and running. To add a member to a new
cluster, refer to Section 5.5.1, “ Adding a Member to a Cluster” . To add a member to an existing
cluster, refer to Section 5.5.2, “ Adding a Member to a Running Cluster” . To delete a member from a
cluster, refer to Section 5.5.3, “ Deleting a Member from a Cluster”
.
5.5.1. Adding a Member t o a Clust er
To add a member to a new cluster, follow these steps:
1. Click Clu st er No d e.
2. At the bottom of the right frame (labeled Pro p ert ies), click the Add a Cluster Node button. Clicking that button causes a Node Properties dialog box to be displayed. The
Node Properties dialog box presents text boxes for Clu st er No d e Name and Q u o ru m
Vo t es (refer to
Figure 5.5, “ Adding a Member to a New Cluster” ).
Fig u re 5.5. Ad d in g a Memb er t o a New Clu st er
3. At the Clu st er No d e Name text box, specify a node name. The entry can be a name or an IP address of the node on the cluster subnet.
Note
Each node must be on the same subnet as the node from which you are running the
Clu st er Co n f ig u rat io n T o o l and must be defined either in DNS or in the
/etc/hosts file of each cluster node.
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Note
The node on which you are running the Clu st er Co n f ig u rat io n T o o l must be explicitly added as a cluster member; the node is not automatically added to the cluster configuration as a result of running the Clu st er Co n f ig u rat io n T o o l.
4. Optionally, at the Q u o ru m Vo t es text box, you can specify a value; however in most configurations you can leave it blank. Leaving the Q u o ru m Vo t es text box blank causes the quorum votes value for that node to be set to the default value of 1.
5. Click OK.
Chapt er 5. Configuring Red Hat Clust er Wit h syst em- config- clust er
6. Configure fencing for the node: a. Click the node that you added in the previous step.
b. At the bottom of the right frame (below Pro p ert ies), click Manage Fencing For
This Node. Clicking Manage Fencing For This Node causes the Fence
Configuration dialog box to be displayed.
c. At the Fence Configuration dialog box, bottom of the right frame (below
Pro p ert ies), click Add a New Fence Level. Clicking Add a New Fence Level causes a fence-level element (for example, Fen ce- Level- 1, Fen ce- Level- 2, and so on) to be displayed below the node in the left frame of the Fence Configuration dialog box.
d. Click the fence-level element.
e. At the bottom of the right frame (below Pro p ert ies), click Add a New Fence to
this Level. Clicking Add a New Fence to this Level causes the Fence
Properties dialog box to be displayed.
f. At the Fence Properties dialog box, click the Fen ce Device T yp e drop-down box and select the fence device for this node. Also, provide additional information required (for example, Po rt and Swit ch for an APC Power Device).
g. At the Fence Properties dialog box, click OK. Clicking OK causes a fence device element to be displayed below the fence-level element.
h. To create additional fence devices at this fence level, return to step 6d. Otherwise, proceed to the next step.
i. To create additional fence levels, return to step 6c. Otherwise, proceed to the next step.
j. If you have configured all the fence levels and fence devices for this node, click
Close.
7. Choose File => Save to save the changes to the cluster configuration.
5.5.2. Adding a Member t o a Running Clust er
The procedure for adding a member to a running cluster depends on whether the cluster contains only two nodes or more than two nodes. To add a member to a running cluster, follow the steps in one of the following sections according to the number of nodes in the cluster:
For clusters with only two nodes —
Section 5.5.2.1, “ Adding a Member to a Running Cluster That Contains Only Two Nodes”
For clusters with more than two nodes —
Section 5.5.2.2, “ Adding a Member to a Running Cluster That Contains More Than Two Nodes”
5 .5 .2 .1 . Adding a Me m be r t o a Running Clust e r T hat Co nt ains Only T wo No de s
To add a member to an existing cluster that is currently in operation, and contains only two nodes, follow these steps:
1. Add the node and configure fencing for it as in
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Section 5.5.1, “ Adding a Member to a Cluster”
.
2. Click Send to Cluster to propagate the updated configuration to other running nodes in the cluster.
3. Use the scp command to send the updated /etc/cluster/cluster.conf file from one of the existing cluster nodes to the new node.
4. At the Red Hat Cluster Suite management GUI Clu st er St at u s T o o l tab, disable each service listed under Services.
5. Stop the cluster software on the two running nodes by running the following commands at each node in this order: a. service rgmanager stop b. service gfs stop, if you are using Red Hat GFS c. service clvmd stop, if CLVM has been used to create clustered volumes d. service cman stop
6. Start cluster software on all cluster nodes (including the added one) by running the following commands in this order: a. service cman start b. service clvmd start, if CLVM has been used to create clustered volumes c. service gfs start, if you are using Red Hat GFS d. service rgmanager start
7. Start the Red Hat Cluster Suite management GUI. At the Clu st er Co n f ig u rat io n T o o l tab, verify that the configuration is correct. At the Clu st er St at u s T o o l tab verify that the nodes and services are running as expected.
5 .5 .2 .2 . Adding a Me m be r t o a Running Clust e r T hat Co nt ains More Than T wo No de s
To add a member to an existing cluster that is currently in operation, and contains more than two nodes, follow these steps:
1. Add the node and configure fencing for it as in
Section 5.5.1, “ Adding a Member to a Cluster”
.
2. Click Send to Cluster to propagate the updated configuration to other running nodes in the cluster.
3. Use the scp command to send the updated /etc/cluster/cluster.conf file from one of the existing cluster nodes to the new node.
4. Start cluster services on the new node by running the following commands in this order: a. service cman start b. service clvmd start, if CLVM has been used to create clustered volumes c. service gfs start, if you are using Red Hat GFS
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Chapt er 5. Configuring Red Hat Clust er Wit h syst em- config- clust er d. service rgmanager start
5. Start the Red Hat Cluster Suite management GUI. At the Clu st er Co n f ig u rat io n T o o l tab, verify that the configuration is correct. At the Clu st er St at u s T o o l tab verify that the nodes and services are running as expected.
5.5.3. Delet ing a Member from a Clust er
To delete a member from an existing cluster that is currently in operation, follow these steps:
1. At one of the running nodes (not to be removed), run the Red Hat Cluster Suite management
GUI. At the Clu st er St at u s T o o l tab, under Services, disable or relocate each service that is running on the node to be deleted.
2. Stop the cluster software on the node to be deleted by running the following commands at that node in this order: a. service rgmanager stop b. service gfs stop, if you are using Red Hat GFS c. service clvmd stop, if CLVM has been used to create clustered volumes d. service cman stop
3. At the Clu st er Co n f ig u rat io n T o o l (on one of the running members), delete the member as follows: a. If necessary, click the triangle icon to expand the Clu st er No d es property.
b. Select the cluster node to be deleted. At the bottom of the right frame (labeled
Pro p ert ies), click the Delete Node button.
c. Clicking the Delete Node button causes a warning dialog box to be displayed requesting confirmation of the deletion (
Figure 5.6, “ Confirm Deleting a Member”
).
Fig u re 5.6 . Co n f irm Delet in g a Memb er d. At that dialog box, click Yes to confirm deletion.
e. Propagate the updated configuration by clicking the Send to Cluster button.
(Propagating the updated configuration automatically saves the configuration.)
4. Stop the cluster software on the remaining running nodes by running the following commands at each node in this order: a. service rgmanager stop
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Red Hat Ent erprise Linux 5 Clust er Administ rat ion b. service gfs stop, if you are using Red Hat GFS c. service clvmd stop, if CLVM has been used to create clustered volumes d. service cman stop
5. Start cluster software on all remaining cluster nodes by running the following commands in this order: a. service cman start b. service clvmd start, if CLVM has been used to create clustered volumes c. service gfs start, if you are using Red Hat GFS d. service rgmanager start
6. Start the Red Hat Cluster Suite management GUI. At the Clu st er Co n f ig u rat io n T o o l tab, verify that the configuration is correct. At the Clu st er St at u s T o o l tab verify that the nodes and services are running as expected.
5 .5 .3.1 . Re m o ving a Me m be r fro m a Clust e r at t he Co m m and-Line
If desired, you can also manually relocate and remove cluster members by using the clusvcadm commmand at a shell prompt.
1. To prevent service downtime, any services running on the member to be removed must be relocated to another node on the cluster by running the following command: clusvcadm -r cluster_service_name -m cluster_node_name
Where cluster_service_name is the name of the service to be relocated and
cluster_member_name is the name of the member to which the service will be relocated.
2. Stop the cluster software on the node to be removed by running the following commands at that node in this order: a. service rgmanager stop b. service gfs stop and/or service gfs2 stop, if you are using gfs, gfs2 or both c. umount -a -t gfs and/or umount -a -t gfs2, if you are using either (or both) in conjunction with rgmanager d. service clvmd stop, if CLVM has been used to create clustered volumes e. service cman stop remove
3. To ensure that the removed member does not rejoin the cluster after it reboots, run the following set of commands: chkconfig cman off chkconfig rgmanager off chkconfig clvmd off chkconfig gfs off chkconfig gfs2 off
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Chapt er 5. Configuring Red Hat Clust er Wit h syst em- config- clust er
5.6. Configuring a Failover Domain
A failover domain is a named subset of cluster nodes that are eligible to run a cluster service in the event of a node failure. A failover domain can have the following characteristics:
Unrestricted — Allows you to specify that a subset of members are preferred, but that a cluster service assigned to this domain can run on any available member.
Restricted — Allows you to restrict the members that can run a particular cluster service. If none of the members in a restricted failover domain are available, the cluster service cannot be started
(either manually or by the cluster software).
Unordered — When a cluster service is assigned to an unordered failover domain, the member on which the cluster service runs is chosen from the available failover domain members with no priority ordering.
Ordered — Allows you to specify a preference order among the members of a failover domain. The member at the top of the list is the most preferred, followed by the second member in the list, and so on.
Note
Changing a failover domain configuration has no effect on currently running services.
Note
Failover domains are not required for operation.
By default, failover domains are unrestricted and unordered.
In a cluster with several members, using a restricted failover domain can minimize the work to set up the cluster to run a cluster service (such as httpd), which requires you to set up the configuration identically on all members that run the cluster service). Instead of setting up the entire cluster to run the cluster service, you must set up only the members in the restricted failover domain that you associate with the cluster service.
Note
To configure a preferred member, you can create an unrestricted failover domain comprising only one cluster member. Doing that causes a cluster service to run on that cluster member primarily (the preferred member), but allows the cluster service to fail over to any of the other members.
The following sections describe adding a failover domain, removing a failover domain, and removing members from a failover domain:
Section 5.6.1, “ Adding a Failover Domain”
Section 5.6.2, “ Removing a Failover Domain”
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Red Hat Ent erprise Linux 5 Clust er Administ rat ion
Section 5.6.3, “ Removing a Member from a Failover Domain”
5.6.1. Adding a Failover Domain
To add a failover domain, follow these steps:
1. At the left frame of the Clu st er Co n f ig u rat io n T o o l, click Failo ver Do main s.
2. At the bottom of the right frame (labeled Pro p ert ies), click the Create a Failover
Domain button. Clicking the Create a Failover Domain button causes the Add
Failover Domain dialog box to be displayed.
3. At the Add Failover Domain dialog box, specify a failover domain name at the Name f o r
n ew Failo ver Do main text box and click OK. Clicking OK causes the Failover Domain
Configuration dialog box to be displayed ( Figure 5.7, “ Failover Domain Configuration:
Configuring a Failover Domain” ).
Note
The name should be descriptive enough to distinguish its purpose relative to other names used in your cluster.
70
Fig u re 5.7. Failo ver Do main Co n f ig u rat io n : Co n f ig u rin g a Failo ver Do main
4. Click the Availab le Clu st er No d es drop-down box and select the members for this failover domain.
Chapt er 5. Configuring Red Hat Clust er Wit h syst em- config- clust er
5. To restrict failover to members in this failover domain, click (check) the Rest rict Failo ver T o
T h is Do main s Memb ers checkbox. (With Rest rict Failo ver T o T h is Do main s
Memb ers checked, services assigned to this failover domain fail over only to nodes in this failover domain.)
6. To prioritize the order in which the members in the failover domain assume control of a failed cluster service, follow these steps:
a. Click (check) the Prio rit iz ed List checkbox ( Figure 5.8, “ Failover Domain
Configuration: Adjusting Priority” ). Clicking Prio rit iz ed List causes the Prio rit y
column to be displayed next to the Memb er No d e column.
Fig u re 5.8. Failo ver Do main Co n f ig u rat io n : Ad ju st in g Prio rit y b. For each node that requires a priority adjustment, click the node listed in the Memb er
No d e/Prio rit y columns and adjust priority by clicking one of the Ad ju st Prio rit y arrows. Priority is indicated by the position in the Memb er No d e column and the value in the Prio rit y column. The node priorities are listed highest to lowest, with the highest priority node at the top of the Memb er No d e column (having the lowest
Prio rit y number).
7. Click Close to create the domain.
8. At the Clu st er Co n f ig u rat io n T o o l, perform one of the following actions depending on whether the configuration is for a new cluster or for one that is operational and running:
New cluster — If this is a new cluster, choose File => Save to save the changes to the cluster configuration.
Running cluster — If this cluster is operational and running, and you want to propagate the change immediately, click the Send to Cluster button. Clicking Send to
Cluster automatically saves the configuration change. If you do not want to propagate the change immediately, choose File => Save to save the changes to the cluster
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Red Hat Ent erprise Linux 5 Clust er Administ rat ion configuration.
5.6.2. Removing a Failover Domain
To remove a failover domain, follow these steps:
1. At the left frame of the Clu st er Co n f ig u rat io n T o o l, click the failover domain that you want to delete (listed under Failo ver Do main s).
2. At the bottom of the right frame (labeled Pro p ert ies), click the Delete Failover Domain button. Clicking the Delete Failover Domain button causes a warning dialog box do be displayed asking if you want to remove the failover domain. Confirm that the failover domain identified in the warning dialog box is the one you want to delete and click Yes. Clicking Yes causes the failover domain to be removed from the list of failover domains under Failo ver
Do main s in the left frame of the Clu st er Co n f ig u rat io n T o o l.
3. At the Clu st er Co n f ig u rat io n T o o l, perform one of the following actions depending on whether the configuration is for a new cluster or for one that is operational and running:
New cluster — If this is a new cluster, choose File => Save to save the changes to the cluster configuration.
Running cluster — If this cluster is operational and running, and you want to propagate the change immediately, click the Send to Cluster button. Clicking Send to
Cluster automatically saves the configuration change. If you do not want to propagate the change immediately, choose File => Save to save the changes to the cluster configuration.
5.6.3. Removing a Member from a Failover Domain
To remove a member from a failover domain, follow these steps:
1. At the left frame of the Clu st er Co n f ig u rat io n T o o l, click the failover domain that you want to change (listed under Failo ver Do main s).
2. At the bottom of the right frame (labeled Pro p ert ies), click the Edit Failover Domain
Properties button. Clicking the Edit Failover Domain Properties button causes
the Failover Domain Configuration dialog box to be displayed ( Figure 5.7, “ Failover
Domain Configuration: Configuring a Failover Domain” ).
3. At the Failover Domain Configuration dialog box, in the Memb er No d e column, click the node name that you want to delete from the failover domain and click the Remove
Member from Domain button. Clicking Remove Member from Domain removes the node from the Memb er No d e column. Repeat this step for each node that is to be deleted from the failover domain. (Nodes must be deleted one at a time.)
4. When finished, click Close.
5. At the Clu st er Co n f ig u rat io n T o o l, perform one of the following actions depending on whether the configuration is for a new cluster or for one that is operational and running:
New cluster — If this is a new cluster, choose File => Save to save the changes to the cluster configuration.
Running cluster — If this cluster is operational and running, and you want to propagate the change immediately, click the Send to Cluster button. Clicking Send to
Cluster automatically saves the configuration change. If you do not want to propagate
72
Chapt er 5. Configuring Red Hat Clust er Wit h syst em- config- clust er the change immediately, choose File => Save to save the changes to the cluster configuration.
5.7. Adding Clust er Resources
To specify a resource for a cluster service, follow these steps:
1. On the Reso u rces property of the Clu st er Co n f ig u rat io n T o o l, click the Create a
Resource button. Clicking the Create a Resource button causes the Resource
Configuration dialog box to be displayed.
2. At the Resource Configuration dialog box, under Select a Reso u rce T yp e, click the
drop-down box. At the drop-down box, select a resource to configure. Appendix C, HA
Resource Parameters describes resource parameters.
3. When finished, click OK.
4. Choose File => Save to save the change to the /etc/cluster/cluster.conf
configuration file.
5.8. Adding a Clust er Service t o t he Clust er
To add a cluster service to the cluster, follow these steps:
1. At the left frame, click Services.
2. At the bottom of the right frame (labeled Pro p ert ies), click the Create a Service button.
Clicking Create a Service causes the Add a Service dialog box to be displayed.
3. At the Add a Service dialog box, type the name of the service in the Name text box and click OK. Clicking OK causes the Service Management dialog box to be displayed (refer to
Figure 5.9, “ Adding a Cluster Service”
).
Note
Use a descriptive name that clearly distinguishes the service from other services in the cluster.
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Red Hat Ent erprise Linux 5 Clust er Administ rat ion
74
Fig u re 5.9 . Ad d in g a Clu st er Service
4. If you want to restrict the members on which this cluster service is able to run, choose a
failover domain from the Failo ver Do main drop-down box. (Refer to Section 5.6,
“ Configuring a Failover Domain” for instructions on how to configure a failover domain.)
5. Au t o st art T h is Service checkbox — This is checked by default. If Au t o st art T h is
Service is checked, the service is started automatically when a cluster is started and running. If Au t o st art T h is Service is not checked, the service must be started manually any time the cluster comes up from stopped state.
6. Ru n Exclu sive checkbox — This sets a policy wherein the service only runs on nodes that have no other services running on them. For example, for a very busy web server that is clustered for high availability, it would would be advisable to keep that service on a node alone with no other services competing for his resources — that is, Ru n Exclu sive checked.
On the other hand, services that consume few resources (like NFS and Samba), can run together on the same node without little concern over contention for resources. For those types of services you can leave the Ru n Exclu sive unchecked.
Chapt er 5. Configuring Red Hat Clust er Wit h syst em- config- clust er
Note
Circumstances that require enabling Ru n Exclu sive are rare. Enabling Ru n
Exclu sive can render a service offline if the node it is running on fails and no other nodes are empty.
7. Select a recovery policy to specify how the resource manager should recover from a service failure. At the upper right of the Service Management dialog box, there are three Reco very
Po licy options available:
Rest art — Restart the service in the node the service is currently located. The default setting is Rest art . If the service cannot be restarted in the current node, the service is relocated.
Relo cat e — Relocate the service before restarting. Do not restart the node where the service is currently located.
Disab le — Do not restart the service at all.
8. Click the Add a Shared Resource to this service button and choose the a resource
listed that you have configured in Section 5.7, “ Adding Cluster Resources”
.
Note
If you are adding a Samba-service resource, connect a Samba-service resource directly to the service, not to a resource within a service. That is, at the Service
Management dialog box, use either Create a new resource for this service or Add a Shared Resource to this service; do not use Attach a new
Private Resource to the Selection or Attach a Shared Resource to
the selection.
9. If needed, you may also create a private resource that you can create that becomes a subordinate resource by clicking on the Attach a new Private Resource to the
Selection button. The process is the same as creating a shared resource described in
Section 5.7, “ Adding Cluster Resources” . The private resource will appear as a child to the
shared resource to which you associated with the shared resource. Click the triangle icon next to the shared resource to display any private resources associated.
10. When finished, click OK.
11. Choose File => Save to save the changes to the cluster configuration.
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Note
To verify the existence of the IP service resource used in a cluster service, you must use the
/sbin/ip addr list command on a cluster node. The following output shows the
/sbin/ip addr list command executed on a node running a cluster service:
1: lo: <LOOPBACK,UP> mtu 16436 qdisc noqueue
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP> mtu 1356 qdisc pfifo_fast qlen 1000
link/ether 00:05:5d:9a:d8:91 brd ff:ff:ff:ff:ff:ff
inet 10.11.4.31/22 brd 10.11.7.255 scope global eth0
inet6 fe80::205:5dff:fe9a:d891/64 scope link
inet 10.11.4.240/22 scope global secondary eth0
valid_lft forever preferred_lft forever
5.8.1. Relocat ing a Service in a Clust er
Service relocation functionality allows you to perform maintenance on a cluster member while maintaining application and data availability.
To relocate a service, drag the service icon from the Services Tab onto the member icon in the
Members tab. The cluster manager stops the service on the member on which it was running and restarts it on the new member.
5.9. Propagat ing T he Configurat ion File: New Clust er
For newly defined clusters, you must propagate the configuration file to the cluster nodes as follows:
1. Log in to the node where you created the configuration file.
2. Using the scp command, copy the /etc/cluster/cluster.conf file to all nodes in the cluster.
Note
Propagating the cluster configuration file this way is necessary for the first time a cluster is created. Once a cluster is installed and running, the cluster configuration file is propagated using the Red Hat cluster management GUI Send to Cluster button.
For more information about propagating the cluster configuration using the GUI Send
to Cluster button, refer to Section 6.3, “ Modifying the Cluster Configuration”
.
5.10. St art ing t he Clust er Soft ware
After you have propagated the cluster configuration to the cluster nodes you can either reboot each node or start the cluster software on each cluster node by running the following commands at each node in this order:
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Chapt er 5. Configuring Red Hat Clust er Wit h syst em- config- clust er
1. service cman start
2. service clvmd start, if CLVM has been used to create clustered volumes
Note
Shared storage for use in Red Hat Cluster Suite requires that you be running the cluster logical volume manager daemon ( clvmd) or the High Availability Logical
Volume Management agents (HA-LVM). If you are not able to use either the clvmd daemon or HA-LVM for operational reasons or because you do not have the correct entitlements, you must not use single-instance LVM on the shared disk as this may result in data corruption. If you have any concerns please contact your Red Hat service representative.
3. service gfs start, if you are using Red Hat GFS
4. service rgmanager start
5. Start the Red Hat Cluster Suite management GUI. At the Clu st er Co n f ig u rat io n T o o l tab, verify that the configuration is correct. At the Clu st er St at u s T o o l tab verify that the nodes and services are running as expected.
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Chapter 6. Managing Red Hat Cluster With system-configcluster
This chapter describes various administrative tasks for managing a Red Hat Cluster and consists of the following sections:
Section 6.1, “ Starting and Stopping the Cluster Software”
Section 6.2, “ Managing High-Availability Services”
Section 6.4, “ Backing Up and Restoring the Cluster Database”
Section 6.6, “ Disabling the Cluster Software”
Section 6.7, “ Diagnosing and Correcting Problems in a Cluster”
Note
While system-config-cluster provides several convenient tools for configuring and managing a Red Hat Cluster, the newer, more comprehensive tool, Co n g a, provides more convenience and flexibility than system-config-cluster. You may want to consider using
Co n g a instead (refer to Chapter 3, Configuring Red Hat Cluster With Conga
Managing Red Hat Cluster With Conga ).
6.1. St art ing and St opping t he Clust er Soft ware
To start the cluster software on a member, type the following commands in this order:
1. service cman start
2. service clvmd start, if CLVM has been used to create clustered volumes
3. service gfs start, if you are using Red Hat GFS
4. service rgmanager start
To stop the cluster software on a member, type the following commands in this order:
1. service rgmanager stop
2. service gfs stop, if you are using Red Hat GFS
3. service clvmd stop, if CLVM has been used to create clustered volumes
4. service cman stop
Stopping the cluster services on a member causes its services to fail over to an active member.
6.2. Managing High-Availabilit y Services
You can manage cluster services with the Clu st er St at u s T o o l (
Figure 6.1, “ Cluster Status Tool” )
through the Clu st er Man ag emen t tab in Cluster Administration GUI.
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Chapt er 6 . Managing Red Hat Clust er Wit h syst em- config- clust er
Fig u re 6 .1. Clu st er St at u s T o o l
You can use the Clu st er St at u s T o o l to enable, disable, restart, or relocate a high-availability service. The Clu st er St at u s T o o l displays the current cluster status in the Services area and automatically updates the status every 10 seconds.
To enable a service, you can select the service in the Services area and click En ab le. To disable a service, you can select the service in the Services area and click Disab le. To restart a service, you can select the service in the Services area and click Rest art . To relocate a service from one node to another, you can drag the service to another node and drop the service onto that node. Relocating a service restarts the service on that node. (Relocating a service to its current node — that is, dragging a service to its current node and dropping the service onto that node — restarts the service.)
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The following tables describe the members and services status information displayed by the Clu st er
St at u s T o o l.
T ab le 6 .1. Memb ers St at u s
Memb ers St at u s
Memb er
Dead
Descrip t io n
The node is part of the cluster.
Note: A node can be a member of a cluster; however, the node may be inactive and incapable of running services. For example, if rgmanager is not running on the node, but all other cluster software components are running in the node, the node appears as a Memb er in the Clu st er
St at u s T o o l.
The node is unable to participate as a cluster member. The most basic cluster software is not running on the node.
T ab le 6 .2. Services St at u s
Services St at u s
St art ed
Pen d in g
Disab led
St o p p ed
Failed
Descrip t io n
The service resources are configured and available on the cluster system that owns the service.
The service has failed on a member and is pending start on another member.
The service has been disabled, and does not have an assigned owner. A disabled service is never restarted automatically by the cluster.
The service is not running; it is waiting for a member capable of starting the service. A service remains in the stopped state if autostart is disabled.
The service has failed to start on the cluster and cannot successfully stop the service. A failed service is never restarted automatically by the cluster.
6.3. Modifying t he Clust er Configurat ion
To modify the cluster configuration (the cluster configuration file ( /etc/cluster/cluster.conf), use the Clu st er Co n f ig u rat io n T o o l. For more information about using the Clu st er
Warning
Do not manually edit the contents of the /etc/cluster/cluster.conf file without guidance from an authorized Red Hat representative or unless you fully understand the consequences of editing the /etc/cluster/cluster.conf file manually.
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Important
Although the Clu st er Co n f ig u rat io n T o o l provides a Q u o ru m Vo t es parameter in the
Properties dialog box of each cluster member, that parameter is intended only for use during initial cluster configuration. Furthermore, it is recommended that you retain the default
Q u o ru m Vo t es value of 1. For more information about using the Clu st er Co n f ig u rat io n
T o o l, refer to Chapter 5, Configuring Red Hat Cluster With system-config-cluster .
To edit the cluster configuration file, click the Clu st er Co n f ig u rat io n tab in the cluster configuration GUI. Clicking the Clu st er Co n f ig u rat io n tab displays a graphical representation of the cluster configuration. Change the configuration file according the following steps:
1. Make changes to cluster elements (for example, create a service).
2. Propagate the updated configuration file throughout the cluster by clicking Send to
Cluster.
Note
The Clu st er Co n f ig u rat io n T o o l does not display the Send to Cluster button if the cluster is new and has not been started yet, or if the node from which you are running the Clu st er Co n f ig u rat io n T o o l is not a member of the cluster. If the Send
to Cluster button is not displayed, you can still use the Clu st er Co n f ig u rat io n
T o o l; however, you cannot propagate the configuration. You can still save the configuration file. For information about using the Clu st er Co n f ig u rat io n T o o l for
3. Clicking Send to Cluster causes a Warning dialog box to be displayed. Click Yes to save and propagate the configuration.
4. Clicking Yes causes an Information dialog box to be displayed, confirming that the current configuration has been propagated to the cluster. Click OK.
5. Click the Clu st er Man ag emen t tab and verify that the changes have been propagated to the cluster members.
6.4 . Backing Up and Rest oring t he Clust er Dat abase
The Clu st er Co n f ig u rat io n T o o l automatically retains backup copies of the three most recently used configuration files (besides the currently used configuration file). Retaining the backup copies is useful if the cluster does not function correctly because of misconfiguration and you need to return to a previous working configuration.
Each time you save a configuration file, the Clu st er Co n f ig u rat io n T o o l saves backup copies of the three most recently used configuration files as /etc/cluster/cluster.conf.bak.1,
/etc/cluster/cluster.conf.bak.2, and /etc/cluster/cluster.conf.bak.3. The backup file /etc/cluster/cluster.conf.bak.1 is the newest backup,
/etc/cluster/cluster.conf.bak.2 is the second newest backup, and
/etc/cluster/cluster.conf.bak.3 is the third newest backup.
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If a cluster member becomes inoperable because of misconfiguration, restore the configuration file according to the following steps:
1. At the Clu st er Co n f ig u rat io n T o o l tab of the Red Hat Cluster Suite management GUI, click
File => O p en .
2. Clicking File = > O p en causes the system-config-cluster dialog box to be displayed.
3. At the system-config-cluster dialog box, select a backup file (for example,
/etc/cluster/cluster.conf.bak.1). Verify the file selection in the Select io n box and click OK.
4. Increment the configuration version beyond the current working version number as follows: a. Click Clu st er => Ed it Clu st er Pro p ert ies.
b. At the Cluster Properties dialog box, change the Co n f ig Versio n value and click OK.
5. Click File => Save As.
6. Clicking File => Save As causes the system-config-cluster dialog box to be displayed.
7. At the system-config-cluster dialog box, select /etc/cluster/cluster.conf and click OK. (Verify the file selection in the Select io n box.)
8. Clicking OK causes an Information dialog box to be displayed. At that dialog box, click OK.
9. Propagate the updated configuration file throughout the cluster by clicking Send to
Cluster.
Note
The Clu st er Co n f ig u rat io n T o o l does not display the Send to Cluster button if the cluster is new and has not been started yet, or if the node from which you are running the Clu st er Co n f ig u rat io n T o o l is not a member of the cluster. If the Send
to Cluster button is not displayed, you can still use the Clu st er Co n f ig u rat io n
T o o l; however, you cannot propagate the configuration. You can still save the configuration file. For information about using the Clu st er Co n f ig u rat io n T o o l for
10. Clicking Send to Cluster causes a Warning dialog box to be displayed. Click Yes to propagate the configuration.
11. Click the Clu st er Man ag emen t tab and verify that the changes have been propagated to the cluster members.
6.5. Disabling Resources of a Clust ered Service for Maint enance
At times, it may be necessary to to stop a resource that is part of a clustered service. You can configure services in the cluster.conf file to have hierarchical resources (similar to a dependency tree) to disable a resource in a service without disabling other resources within that service.
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Chapt er 6 . Managing Red Hat Clust er Wit h syst em- config- clust er
So, for example, if you have a database that uses an ext3-formatted filesystem, you can disable the database while preserving the filesystem resource for use in the service.
In the following example snippet of a cluster.conf file, a service uses a MySQL database and ext3-formatted filesystem resources.
<resources>
<mysql config_file="/etc/my.cnf" name="mysql-resource" shutdown_wait="0"/>
<fs device="/dev/sdb1" force_fsck="0" force_unmount="1" fsid="9349" fstype="ext3" mountpoint="/opt/db" name="SharedDisk" self_fence="0"/>
</resources>
<service name="ha-mysql">
<fs ref="SharedDisk">
<mysql ref="mysql-resource"/>
</fs>
</service>
In order to stop the MySQL-database and perform maintenance tasks without interfering with the cluster software (mainly rgmanager), you must first freeze the clustered service: clusvcadm -Z ha-mysql
You can then stop the MySQL service with the rg_test command: rg_test test /etc/cluster/cluster.conf stop mysql mysql-resource
When the MySQL database has been shutdown, maintenance can be performed. After finishing the maintenance, start the MySQL database with rg_test again: rg_test test /etc/cluster/cluster.conf start mysql mysql-resource
The cluster service is still frozen and will not be monitored by rgmanager. To enable monitoring again, unfreeze the clustered service: clusvcadm -U ha-mysql
Note
The rg_test utility will stop all instances of a resource on a given node, potentially causing undesired results if multiple services on a single node are sharing the same resource. Do not perform these steps on resources that have multiple instances within the cluster.conf file.
In such cases, it is usually necessary to disable the service for maintenance.
6.6. Disabling t he Clust er Soft ware
It may become necessary to temporarily disable the cluster software on a cluster member. For example, if a cluster member experiences a hardware failure, you may want to reboot that member, but prevent it from rejoining the cluster to perform maintenance on the system.
Use the /sbin/chkconfig command to stop the member from joining the cluster at boot-up as follows:
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# chkconfig --level 2345 rgmanager off
# chkconfig --level 2345 gfs off
# chkconfig --level 2345 clvmd off
# chkconfig --level 2345 cman off
Once the problems with the disabled cluster member have been resolved, use the following commands to allow the member to rejoin the cluster:
# chkconfig --level 2345 rgmanager on
# chkconfig --level 2345 gfs on
# chkconfig --level 2345 clvmd on
# chkconfig --level 2345 cman on
You can then reboot the member for the changes to take effect or run the following commands in the order shown to restart cluster software:
1. service cman start
2. service clvmd start, if CLVM has been used to create clustered volumes
3. service gfs start, if you are using Red Hat GFS
4. service rgmanager start
6.7. Diagnosing and Correct ing Problems in a Clust er
For information about diagnosing and correcting problems in a cluster, contact an authorized Red
Hat support representative.
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Example of Set t ing Up Apache HT T P Server
Example of Setting Up Apache HTTP Server
This appendix provides an example of setting up a highly available Apache HTTP Server on a Red
Hat Cluster. The example describes how to set up a service to fail over an Apache HTTP Server.
Variables in the example apply to this example only; they are provided to assist setting up a service that suits your requirements.
Note
This example uses the Clu st er Co n f ig u rat io n T o o l ( system-config-cluster). You can use comparable Co n g a functions to make an Apache HTTP Server highly available on a Red
Hat Cluster.
A.1. Apache HT T P Server Set up Overview
First, configure Apache HTTP Server on all nodes in the cluster. If using a failover domain , assign
the service to all cluster nodes configured to run the Apache HTTP Server. Refer to Section 5.6,
system runs the Apache HTTP Server at one time. The example configuration consists of installing the httpd RPM package on all cluster nodes (or on nodes in the failover domain, if used) and configuring a shared GFS shared resource for the Web content.
When installing the Apache HTTP Server on the cluster systems, run the following command to ensure that the cluster nodes do not automatically start the service when the system boots:
# chkconfig --del httpd
Rather than having the system init scripts spawn the httpd daemon, the cluster infrastructure initializes the service on the active cluster node. This ensures that the corresponding IP address and file system mounts are active on only one cluster node at a time.
When adding an httpd service, a floating IP address must be assigned to the service so that the IP address will transfer from one cluster node to another in the event of failover or service relocation.
The cluster infrastructure binds this IP address to the network interface on the cluster system that is currently running the Apache HTTP Server. This IP address ensures that the cluster node running
httpd is transparent to the clients accessing the service.
The file systems that contain the Web content cannot be automatically mounted on the shared storage resource when the cluster nodes boot. Instead, the cluster software must mount and unmount the file system as the httpd service is started and stopped. This prevents the cluster systems from accessing the same data simultaneously, which may result in data corruption. Therefore, do not include the file systems in the /etc/fstab file.
A.2. Configuring Shared St orage
To set up the shared file system resource, perform the following tasks as root on one cluster system:
1. On one cluster node, use the interactive parted utility to create a partition to use for the document root directory. Note that it is possible to create multiple document root directories on different disk partitions.
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2. Use the mkfs command to create an ext3 file system on the partition you created in the previous step. Specify the drive letter and the partition number. For example:
# mkfs -t ext3 /dev/sde3
3. Mount the file system that contains the document root directory. For example:
# mount /dev/sde3 /var/www/html
Do not add this mount information to the /etc/fstab file because only the cluster software can mount and unmount file systems used in a service.
4. Copy all the required files to the document root directory.
5. If you have CGI files or other files that must be in different directories or in separate partitions, repeat these steps, as needed.
A.3. Inst alling and Configuring t he Apache HT T P Server
The Apache HTTP Server must be installed and configured on all nodes in the assigned failover domain, if used, or in the cluster. The basic server configuration must be the same on all nodes on which it runs for the service to fail over correctly. The following example shows a basic Apache HTTP
Server installation that includes no third-party modules or performance tuning.
On all node in the cluster (or nodes in the failover domain, if used), install the httpd RPM package.
For example:
rpm -Uvh httpd-<version>.<arch>.rpm
To configure the Apache HTTP Server as a cluster service, perform the following tasks:
1. Edit the /etc/httpd/conf/httpd.conf configuration file and customize the file according to your configuration. For example:
Specify the directory that contains the HTML files. Also specify this mount point when adding the service to the cluster configuration. It is only required to change this field if the mount point for the web site's content differs from the default setting of /var/www/html/.
For example:
DocumentRoot "/mnt/httpdservice/html"
Specify a unique IP address to which the service will listen for requests. For example:
Listen 192.168.1.100:80
This IP address then must be configured as a cluster resource for the service using the
Clu st er Co n f ig u rat io n T o o l.
If the script directory resides in a non-standard location, specify the directory that contains the CGI programs. For example:
ScriptAlias /cgi-bin/ "/mnt/httpdservice/cgi-bin/"
Specify the path that was used in the previous step, and set the access permissions to default to that directory. For example:
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Example of Set t ing Up Apache HT T P Server
<Directory /mnt/httpdservice/cgi-bin">
AllowOverride None
Options None
Order allow,deny
Allow from all
</Directory>
Additional changes may need to be made to tune the Apache HTTP Server or add module functionality. For information on setting up other options, refer to the Red Hat Enterprise
Linux System Administration Guide and the Red Hat Enterprise Linux Reference Guide.
2. The standard Apache HTTP Server start script, /etc/rc.d/init.d/httpd is also used within the cluster framework to start and stop the Apache HTTP Server on the active cluster node. Accordingly, when configuring the service, specify this script by adding it as a Scrip t resource in the Clu st er Co n f ig u rat io n T o o l.
3. Copy the configuration file over to the other nodes of the cluster (or nodes of the failover domain, if configured).
Before the service is added to the cluster configuration, ensure that the Apache HTTP Server directories are not mounted. Then, on one node, invoke the Clu st er Co n f ig u rat io n T o o l to add the service, as follows. This example assumes a failover domain named httpd-domain was created for this service.
1. Add the init script for the Apache HTTP Server service.
Select the Reso u rces tab and click Create a Resource. The Resources
Configuration properties dialog box is displayed.
Select Scrip t form the drop down menu.
Enter a Name to be associated with the Apache HTTP Server service.
Specify the path to the Apache HTTP Server init script (for example,
/etc/rc.d/init.d/httpd) in the File ( wit h p at h ) field.
Click OK.
2. Add a device for the Apache HTTP Server content files and/or custom scripts.
Click Create a Resource.
In the Resource Configuration dialog, select File Syst em from the drop-down menu.
Enter the Name for the resource (for example, httpd-content.
Choose ext 3 from the File Syst em T yp e drop-down menu.
Enter the mount point in the Mo u n t Po in t field (for example, /var/www/html/).
Enter the device special file name in the Device field (for example, /dev/sda3).
3. Add an IP address for the Apache HTTP Server service.
Click Create a Resource.
Choose IP Ad d ress from the drop-down menu.
Enter the IP Ad d ress to be associated with the Apache HTTP Server service.
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Make sure that the Mo n it o r Lin k checkbox is left checked.
Click OK.
4. Click the Services property.
5. Create the Apache HTTP Server service.
Click Create a Service. Type a Name for the service in the Add a Service dialog.
In the Service Management dialog, select a Failo ver Do main from the drop-down menu or leave it as No n e.
Click the Add a Shared Resource to this service button. From the available list, choose each resource that you created in the previous steps. Repeat this step until all resources have been added.
Click OK.
6. Choose File => Save to save your changes.
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Fence Device Parameters
This appendix provides tables with parameter descriptions of fence devices.
Fence Device Paramet ers
Note
The Name parameter for a fence device specifies an arbitrary name for the device that will be used by Red Hat Cluster Suite. This is not the same as the DNS name for the device.
Note
Certain fence devices have an optional Passwo rd Scrip t parameter. The Passwo rd Scrip t parameter allows specifying that a fence-device password is supplied from a script rather than from the Passwo rd parameter. Using the Passwo rd Scrip t parameter supersedes the
Passwo rd parameter, allowing passwords to not be visible in the cluster configuration file
( /etc/cluster/cluster.conf).
T ab le B.1. APC Po wer Swit ch
Field
Name
IP Address
Login
Password
Password
Script
(optional)
Power wait
Port
Switch
(optional)
Use SSH fence_apc
Descrip t io n
A name for the APC device connected to the cluster.
The IP address assigned to the device.
The login name used to access the device.
The password used to authenticate the connection to the device.
The script that supplies a password for access to the fence device. Using this supersedes the Passwo rd parameter.
Number of seconds to wait after issuing a power off or power on command.
The port.
The switch number for the APC switch that connects to the node when you have multiple daisy-chained switches.
(Red Hat Enterprise Linux 5.4 and later) Indicates that system will use SSH to access the device.
The fence agent for APC.
T ab le B.2. APC Po wer Swit ch o ver SNMP ( Red Hat En t erp rise Lin u x 5.2 an d lat er)
Field
Name
IP Address
UDP/TCP Port
Login
Password
Password Script
(optional)
Descrip t io n
A name for the APC device connected to the cluster into which the fence daemon logs via the SNMP protocol.
The IP address or hostname assigned to the device.
The UDP/TCP port to use for connection with the device; the default value is
161.
The login name used to access the device.
The password used to authenticate the connection to the device.
The script that supplies a password for access to the fence device. Using this supersedes the Passwo rd parameter.
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Field Descrip t io n
SNMP version
SNMP community
The SNMP version to use (1, 2c, 3); the default value is 1.
The SNMP community string; the default value is private.
SNMP security level The SNMP security level (noAuthNoPriv, authNoPriv, authPriv).
SNMP authentication protocol
The SNMP authentication protocol (MD5, SHA).
The SNMP privacy protocol (DES, AES).
SNMP privacy protocol
SNMP privacy protocol password
SNMP privacy protocol script
The SNMP privacy protocol password.
The script that supplies a password for SNMP privacy protocol. Using this supersedes the SNMP p rivacy p ro t o co l p asswo rd parameter.
Power wait
Port fence_apc_snmp
Number of seconds to wait after issuing a power off or power on command.
The port.
The fence agent for APC that logs into the SNP device via the SNMP protocol.
T ab le B.3. Bro cad e Fab ric Swit ch
Field
Name
IP Address
Login
Password
Password
Script
(optional)
Port fence_broca de
Descrip t io n
A name for the Brocade device connected to the cluster.
The IP address assigned to the device.
The login name used to access the device.
The password used to authenticate the connection to the device.
The script that supplies a password for access to the fence device. Using this supersedes the Passwo rd parameter.
The switch outlet number.
The fence agent for Brocade FC switches.
T ab le B.4 . Bu ll PAP ( Plat f o rm Ad min ist rat io n Pro cesso r)
Field
Name
IP Address
Login
Password
Password
Script
(optional)
Domain fence_bullp ap
Descrip t io n
A name for the Bull PAP system connected to the cluster.
The IP address assigned to the PAP console.
The login name used to access the PAP console.
The password used to authenticate the connection to the PAP console.
The script that supplies a password for access to the fence device. Using this supersedes the Passwo rd parameter.
Domain of the Bull PAP system to power cycle.
The fence agent for Bull’s NovaScale machines controlled by PAP management consoles.
T ab le B.5. Cisco MDS ( Red Hat En t erp rise Lin u x 5.4 an d lat er)
Field
Name
Descrip t io n
A name for the Cisco MDS 9000 series device with SNMP enabled.
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Fence Device Paramet ers
Field Descrip t io n
IP address or hostname
UDP/TCP port
(optional)
Login
Password
Password Script
(optional)
SNMP privacy protocol password
SNMP privacy protocol script
The IP address or hostname assigned to the device.
The UDP/TCP port to use for connection with the device; the default value is
161.
The login name used to access the device.
The password used to authenticate the connection to the device.
The script that supplies a password for access to the fence device. Using this supersedes the Passwo rd parameter.
SNMP version
SNMP community
The SNMP version to use (1, 2c, 3).
The SNMP community string.
SNMP security level The SNMP security level (noAuthNoPriv, authNoPriv, authPriv).
SNMP authentication protocol
The SNMP authentication protocol (MD5, SHA).
SNMP privacy protocol
The SNMP privacy protocol (DES, AES).
The SNMP privacy protocol password.
The script that supplies a password for SNMP privacy protocol. Using this supersedes the SNMP p rivacy p ro t o co l p asswo rd parameter.
Power wait
Port
Number of seconds to wait after issuing a power off or power on command.
The port.
fence_cisco_mds The fence agent for Cisco MDS.
T ab le B.6 . Cisco UCS ( Red Hat En t erp rise Lin u x 5.6 an d lat er)
Field Descrip t io n
Name
IP Address
IP port (optional)
Login
Password
Password Script
(optional)
Use SSL connections
A name for the Cisco UCS device.
The IP address or hostname assigned to the device.
The TCP port to use to connect to the device.
The login name used to access the device.
The password used to authenticate the connection to the device.
The script that supplies a password for access to the fence device. Using this supersedes the Passwo rd parameter.
Use SSL connections to communicate with the device.
Sub-organization
Power wait
Additional path needed to access suborganization.
Number of seconds to wait after issuing a power off or power on command.
Port Name of virtual machine.
fence_cisco_ucs The fence agent for Cisco UCS.
T ab le B.7. Dell DRAC
Field
Name
IP Address
Login
Password
Descrip t io n
The name assigned to the DRAC.
The IP address assigned to the DRAC.
The login name used to access the DRAC.
The password used to authenticate the connection to the DRAC.
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Field Descrip t io n
Module Name (optional) The module name for the DRAC when you have multiple DRAC modules.
Password
Script
(optional)
The script that supplies a password for access to the fence device. Using this supersedes the Passwo rd parameter.
Use SSH
(DRAC5 only)
Power wait fence_drac
(Red Hat Enterprise Linux 5.4 and later) Indicates that system will use SSH to access the device.
Number of seconds to wait after issuing a power off or power on command.
The fence agent for Dell Remote Access Card (DRAC).
T ab le B.8. Eg en era SAN Co n t ro ller
Field
Name
CServer
Descrip t io n
A name for the BladeFrame device connected to the cluster.
The hostname (and optionally the username in the form of
username@hostname) assigned to the device. Refer to the fence_egenera(8) man page for more information.
The path to the esh command on the cserver (default is /opt/pan- mgr/bin/esh) ESH Path
(optional) lpan pserver fence_egene ra
The logical process area network (LPAN) of the device.
The processing blade (pserver) name of the device.
The fence agent for the Egenera BladeFrame.
T ab le B.9 . Fu jit su Siemen s Remo t eview Service Bo ard ( RSB)
Field
Name
Hostname
Login
Password
Password
Script
(optional) fence_rsb
Descrip t io n
A name for the RSB to use as a fence device.
The hostname assigned to the device.
The login name used to access the device.
The password used to authenticate the connection to the device.
The script that supplies a password for access to the fence device. Using this supersedes the Passwo rd parameter.
The fence agent for Fujitsu-Siemens RSB.
T ab le B.10. G NBD ( G lo b al Net wo rk Blo ck Device)
Field
Name
Servers
IP Address fence_gnbd
Descrip t io n
A name for the GNBD device used to fence the cluster. Note that the GFS server must be accessed via GNBD for cluster node fencing support.
The hostname of the server to fence the client from, in either IP address or hostname form. For multiple hostnames, separate each hostname with a whitespace.
The cluster name of the node to be fenced. Refer to the fence_gnbd(8) man page for more information.
The fence agent for GNBD-based GFS clusters.
T ab le B.11. HP iLO ( In t eg rat ed Lig h t s O u t )
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Fence Device Paramet ers
Field
Name
Hostname
Login
Password
Password
Script
(optional)
Use SSL connections
Power wait fence_ilo
Descrip t io n
A name for the server with HP iLO support.
The hostname assigned to the device.
The login name used to access the device.
The password used to authenticate the connection to the device.
The script that supplies a password for access to the fence device. Using this supersedes the Passwo rd parameter.
Use SSL connections to communicate with the device.
Number of seconds to wait after issuing a power off or power on command.
The fence agent for HP servers with the Integrated Light Out (iLO) PCI card.
T ab le B.12. HP iLO ( In t eg rat ed Lig h t s O u t ) MP ( Red Hat En t erp rise Lin u x 5.5 an d lat er)
Field
Name
Hostname
IP port (optional)
Login
Password
Password Script
(optional)
Use SSH
Descrip t io n
A name for the server with HP iLO support.
The hostname assigned to the device.
TCP port to use for connection with the device.
The login name used to access the device.
The password used to authenticate the connection to the device.
The script that supplies a password for access to the fence device. Using this supersedes the Passwo rd parameter.
(Red Hat Enterprise Linux 5.4 and later) Indicates that system will use SSH to access the device.
The identity file for SSH.
Path to SSH identity file
Force command prompt
Power wait fence_ilo_mp
The command prompt to use. The default value is ’MP>’, ’hpiLO->’.
Number of seconds to wait after issuing a power off or power on command.
The fence agent for HP iLO MP devices.
T ab le B.13. IBM Blad e Cen t er
Field
Name
IP Address
Login
Password
Password
Script
(optional)
Power wait
Blade
Use SSH fence_blade center
Descrip t io n
A name for the IBM BladeCenter device connected to the cluster.
The IP address assigned to the device.
The login name used to access the device.
The password used to authenticate the connection to the device.
The script that supplies a password for access to the fence device. Using this supersedes the Passwo rd parameter.
Number of seconds to wait after issuing a power off or power on command.
The blade of the device.
(Red Hat Enterprise Linux 5.4 and later) Indicates that system will use SSH to access the device.
The fence agent for IBM BladeCenter.
T ab le B.14 . IBM iPDU ( Red Hat En t erp rise Lin u x 5.9 an d lat er)
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Field Descrip t io n
Name A name for the IBM iPDU device connected to the cluster into which the fence daemon logs via the SNMP protocol.
The IP address or hostname assigned to the device.
IP Address
UDP/TCP Port
Login
Password
Password Script
(optional)
SNMP version
The UDP/TCP port to use for connection with the device; the default value is
161.
The login name used to access the device.
The password used to authenticate the connection to the device.
The script that supplies a password for access to the fence device. Using this supersedes the Passwo rd parameter.
The SNMP version to use (1, 2c, 3); the default value is 1.
SNMP community The SNMP community string; the default value is private.
SNMP security level The SNMP security level (noAuthNoPriv, authNoPriv, authPriv).
The SNMP authentication protocol (MD5, SHA).
SNMP authentication protocol
SNMP privacy protocol
SNMP privacy protocol password
SNMP privacy protocol script
Power wait
Port fence_ipdu
The SNMP privacy protocol (DES, AES).
The SNMP privacy protocol password.
The script that supplies a password for SNMP privacy protocol. Using this supersedes the SNMP p rivacy p ro t o co l p asswo rd parameter.
Number of seconds to wait after issuing a power off or power on command.
The port.
The fence agent for iPDU over SNMP.
T ab le B.15. IBM Remo t e Su p erviso r Ad ap t er II ( RSA II)
Field
Name
Hostname
Login
Password
Password
Script
(optional)
Power wait fence_rsa
Descrip t io n
A name for the RSA device connected to the cluster.
The hostname assigned to the device.
The login name used to access the device.
The password used to authenticate the connection to the device.
The script that supplies a password for access to the fence device. Using this supersedes the Passwo rd parameter.
Number of seconds to wait after issuing a power off or power on command.
The fence agent for the IBM RSA II management interface.
T ab le B.16 . IF MIB ( Red Hat En t erp rise Lin u x 5.6 an d lat er)
Field
Name
IP address or hostname
UDP/TCP port
(optional)
Login
Password
Descrip t io n
A name for the IF MIB device connected to the cluster.
The IP address or hostname assigned to the device.
The UDP/TCP port to use for connection with the device; the default value is
161.
The login name used to access the device.
The password used to authenticate the connection to the device.
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Field Descrip t io n
Password Script
(optional)
SNMP version
SNMP community
Power wait
Port fence_ifmib
The script that supplies a password for access to the fence device. Using this supersedes the Passwo rd parameter.
The SNMP version to use (1, 2c, 3); the default value is 1.
The SNMP community string.
SNMP security level The SNMP security level (noAuthNoPriv, authNoPriv, authPriv).
SNMP authentication protocol
The SNMP authentication protocol (MD5, SHA).
The SNMP privacy protocol (DES, AES).
SNMP privacy protocol
SNMP privacy protocol password
The SNMP privacy protocol password.
SNMP privacy protocol script
The script that supplies a password for SNMP privacy protocol. Using this supersedes the SNMP p rivacy p ro t o co l p asswo rd parameter.
Number of seconds to wait after issuing a power off or power on command.
Physical plug number or name of virtual machine.
The fence agent for IF-MIB devices.
T ab le B.17. IPMI ( In t ellig en t Plat f o rm Man ag emen t In t erf ace) LAN
Field Descrip t io n
Name
IP Address
A name for the IPMI LAN device connected to the cluster.
The IP address assigned to the IPMI port.
Login The login name of a user capable of issuing power on/off commands to the given IPMI port.
The password used to authenticate the connection to the IPMI port.
Password
Password Script (optional) The script that supplies a password for access to the fence device.
Using this supersedes the Passwo rd parameter.
Authentication Type none, password, md2, or md5.
Privilege Level
Use Lanplus fence_ipmilan
The privilege level on the IPMI device.
True or 1. If blank, then value is False.
The fence agent for machines controlled by IPMI.
T ab le B.18. Man u al Fen cin g
Field
Name
Descrip t io n
A name to assign the Manual fencing agent. Refer to the fence_manual(8) man page for more information.
Warning
Manual fencing is not supported for production environments.
T ab le B.19 . McDat a SAN Swit ch
Field
Name
Descrip t io n
A name for the McData device connected to the cluster.
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Field
IP Address
Login
Password
Password
Script
(optional)
Port fence_mcdat a
Descrip t io n
The IP address assigned to the device.
The login name used to access the device.
The password used to authenticate the connection to the device.
The script that supplies a password for access to the fence device. Using this supersedes the Passwo rd parameter.
The switch outlet number.
The fence agent for McData FC switches.
T ab le B.20. Q Lo g ic SANBo x2 Swit ch
Field
Name
IP Address
Login
Password
Password
Script
(optional)
Power wait
Port fence_sanbo x2
Descrip t io n
A name for the SANBox2 device connected to the cluster.
The IP address assigned to the device.
The login name used to access the device.
The password used to authenticate the connection to the device.
The script that supplies a password for access to the fence device. Using this supersedes the Passwo rd parameter.
Number of seconds to wait after issuing a power off or power on command.
The switch outlet number.
The fence agent for QLogic SANBox2 FC switches.
T ab le B.21. RHEV- M REST API ( RHEL 5.8 an d lat er ag ain st RHEV 3.0 an d lat er)
Field Descrip t io n
Name
IP Address
IP port
(optional)
Login
Password
Password
Script
(optional)
Use SSL connections
Name of the RHEV-M REST API fencing device.
The IP address or hostname assigned to the device.
The TCP port to use for connection with the device.
The login name used to access the device.
The password used to authenticate the connection to the device.
The script that supplies a password for access to the fence device. Using this supersedes the Passwo rd parameter.
Use SSL connections to communicate with the device.
Power wait
Port
Number of seconds to wait after issuing a power off or power on command.
Physical plug number or name of virtual machine.
fence_rhevm The fence agent for RHEV-M REST API.
T ab le B.22. RPS- 10 Po wer Swit ch ( t wo - n o d e clu st ers o n ly)
Field
Name
Device Name
Descrip t io n
A name for the WTI RPS-10 power switch connected to the cluster.
The device name of the device the switch is connected to on the controlling host
(for example, /dev/ttys2).
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Field
Port fence_wti
Descrip t io n
The switch outlet number.
The fence agent for the WTI Network Power Switch.
T ab le B.23. SCSI Fen cin g
Field
Name
Node name fence_scsi
Descrip t io n
A name for the SCSI fence device.
Name of the node to be fenced. Refer to the fence_scsi(8) man page for more information.
The fence agent for SCSI persistent reservations.
Note
Use of SCSI persistent reservations as a fence method is supported with the following limitations:
As of Red Hat Enterprise Linux 5.5 and fully-updated releases of Red Hat Enterprise Linux
5.4, SCSI fencing can be used in a 2-node cluster; previous releases did not support this feature.
When using SCSI fencing, all nodes in the cluster must register with the same devices so that each node can remove another node's registration key from all the devices it is registered with.
Devices used for the cluster volumes should be a complete LUN, not partitions. SCSI persistent reservations work on an entire LUN, meaning that access is controlled to each
LUN, not individual partitions.
As of Red Hat Enterprise Linux 5.5 and fully-updated releases of Red Hat Enterprise Linux
5.4, SCSI fencing can be used in conjunction with qdisk; previous releases did not support this feature. You cannot use fence_scsi on the LUN where qdiskd resides; it must be a raw LUN or raw partition of a LUN.
T ab le B.24 . Virt u al Mach in e Fen cin g
Field
Name
Domain
Descrip t io n
Name of the virtual machine fencing device.
Unique domain name of the guest to be fenced.
T ab le B.25. VMware ( SO AP In t erf ace) ( Red Hat En t erp rise Lin u x 5.7 an d lat er)
Field
Name
Hostname
IP port
(optional)
Login
Password
Password
Script
(optional)
Descrip t io n
Name of the virtual machine fencing device.
The IP address or hostname assigned to the device.
The TCP port to use for connection with the device.
The login name used to access the device.
The password used to authenticate the connection to the device.
The script that supplies a password for access to the fence device. Using this supersedes the Passwo rd parameter.
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Field
Use SSL connections
Power wait
Virtual machine name
Virtual machine UUID fence_vmwar e_soap
Descrip t io n
Use SSL connections to communicate with the device.
Number of seconds to wait after issuing a power off or power on command.
Name of virtual machine in inventory path format (e.g.,
/datacenter/vm/Discovered_virtual_machine/myMachine).
The UUID of the virtual machine to fence.
The fence agent for VMWare over SOAP API.
T ab le B.26 . Vixel SAN Swit ch
Field Descrip t io n
Name
IP Address
Password
Password
Script
(optional)
A name for the Vixel switch connected to the cluster.
The IP address assigned to the device.
The password used to authenticate the connection to the device.
The script that supplies a password for access to the fence device. Using this supersedes the Passwo rd parameter.
Port The switch outlet number.
fence_vixel The fence agent for Vixel switches.
T ab le B.27. WT I Po wer Swit ch
Field
Name
IP Address
Password
Password
Script
(optional)
Power wait
Port
Use SSH fence_wti
Descrip t io n
A name for the WTI power switch connected to the cluster.
The IP address assigned to the device.
The password used to authenticate the connection to the device.
The script that supplies a password for access to the fence device. Using this supersedes the Passwo rd parameter.
Number of seconds to wait after issuing a power off or power on command.
The switch outlet number.
(Red Hat Enterprise Linux 5.4 and later) Indicates that system will use SSH to access the device.
The fence agent for the WTI network power switch.
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HA Resource Parameters
This appendix provides descriptions of HA resource parameters. You can configure the parameters
with Lu ci, system-config-cluster, or by editing etc/cluster/cluster.conf. Table C.1, “ HA
Resource Summary” lists the resources, their corresponding resource agents, and references to other
tables containing parameter descriptions. To understand resource agents in more detail you can view them in /usr/share/cluster of any cluster node.
For a comprehensive list and description of cluster.conf elements and attributes, refer to the cluster schema at /usr/share/system-config-cluster/misc/cluster.ng, and the annotated schema at /usr/share/doc/system-config-cluster-
X.Y.ZZ/cluster_conf.html (for example /usr/share/doc/system-config-cluster-
1.0.57/cluster_conf.html).
T ab le C.1. HA Reso u rce Su mmary
Reso u rce Reso u rce Ag en t Ref eren ce t o Paramet er
Descrip t io n
Apache
File System
GFS File
System
IP Address
LVM
MySQL apache.sh
fs.sh
clusterfs.sh
ip.sh
lvm.sh
mysql.sh
NFS Client
NFS Export
NFS Mount
Open LDAP
Oracle 10g
Failover
Instance nfsclient.sh
nfsexport.sh
netfs.sh
openldap.sh
oracledb.sh
Oracle DB
Agent
Oracle Listener
Agent orainstance.sh
oralistener.sh
PostgreSQL 8 postgres-8.sh
SAP Database SAPDatabase
SAP Instance SAPInstance
Samba smb.sh
Script
Service
Sybase ASE script.sh
service.sh
ASEHAagent.sh
Tomcat 5
Virtual
Machine tomcat-5.sh
vm.sh
Table C.23, “ Virtual Machine”
NOTE: Lu ci displays this as a virtual service if the host cluster can support virtual machines.
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T ab le C.2. Ap ach e Server
Field Descrip t io n
Name
Server Root
Config File
The name of the Apache Service.
The default value is /etc/httpd.
Specifies the Apache configuration file. The default valuer is /etc/httpd/conf.
httpd Options Other command line options for httpd.
Shutdown Wait
(seconds)
Specifies the number of seconds to wait for correct end of service shutdown.
T ab le C.3. File Syst em
Field
Name
File system type
Mount point
Device
Options
Descrip t io n
Specifies a name for the file system resource.
If not specified, mount tries to determine the file system type.
Path in file system hierarchy to mount this file system.
Specifies the device associated with the file system resource. This can be a block device, file system label, or UUID of a file system.
Mount options; that is, options used when the file system is mounted. These may be file-system specific. Refer to the mount(8) man page for supported mount options.
File system ID
Note
File System ID is used only by NFS services.
When creating a new file system resource, you can leave this field blank. Leaving the field blank causes a file system ID to be assigned automatically after you commit the parameter during configuration. If you need to assign a file system ID explicitly, specify it in this field.
Force unmount If enabled, forces the file system to unmount. The default setting is disabled.
Force Unmount kills all processes using the mount point to free up the mount when it tries to unmount.
Reboot host node if unmount fails
Check file system before mounting
If enabled, reboots the node if unmounting this file system fails. The default setting is disabled.
If enabled, causes fsck to be run on the file system before mounting it. The default setting is disabled.
Enable NFS daemon and lockd workaround
If your filesystem is exported via NFS and occasionally fails to unmount (either during shutdown or service relocation), setting this option will drop all filesystem references prior to the unmount operation. Setting this option requires that you enable the Force unmount option. You should set this option as a last resort only, as this is a hard attempt to unmount a file system. You can enable NFS lock workarounds in a soft attempt to unmount a file system at the level of cluster
service configuration, as described in Section 3.9, “ Adding a Cluster Service to the Cluster” .
T ab le C.4 . G FS
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HA Resource Paramet ers
T ab le C.4 . G FS
Field
Name
Mount point
Device
File system type
Options
File system ID
Descrip t io n
The name of the file system resource.
The path to which the file system resource is mounted.
The device file associated with the file system resource.
Specify GFS or GFS2.
Mount options.
Note
File System ID is used only by NFS services.
When creating a new GFS resource, you can leave this field blank. Leaving the field blank causes a file system ID to be assigned automatically after you commit the parameter during configuration. If you need to assign a file system ID explicitly, specify it in this field.
Force unmount If enabled, forces the file system to unmount. The default setting is disabled.
Force Unmount kills all processes using the mount point to free up the mount when it tries to unmount. With GFS resources, the mount point is not unmounted at service tear-down unless Force Unmount is enabled.
Reboot host node if unmount fails
If enabled and unmounting the file system fails, the node will immediately reboot.
Generally, this is used in conjunction with force-unmount support, but it is not required.
Enable NFS daemon and lockd workaround
If your filesystem is exported via NFS and occasionally fails to unmount (either during shutdown or service relocation), setting this option will drop all filesystem references prior to the unmount operation. Setting this option requires that you enable the Force unmount option. You should set this option as a last resort only, as this is a hard attempt to unmount a file system. You can enable NFS lock workarounds in a soft attempt to unmount a file system at the level of cluster
service configuration, as described in Section 3.9, “ Adding a Cluster Service to the Cluster” .
T ab le C.5. IP Ad d ress
Field
IP address
Monitor link
Descrip t io n
The IP address for the resource. This is a virtual IP address. IPv4 and IPv6 addresses are supported, as is NIC link monitoring for each IP address.
Enabling this causes the status check to fail if the link on the NIC to which this IP address is bound is not present.
T ab le C.6 . LVM
Field
Name
Volume Group
Name
Logical
Volume Name
Descrip t io n
A unique name for this LVM resource.
A descriptive name of the volume group being managed.
Name of the logical volume being managed. This parameter is optional if there is more than one logical volume in the volume group being managed.
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Field
Fence the node if it is unable to clean up LVM tags
Descrip t io n
Fence the node if it is unable to clean up LVM tags.
T ab le C.7. MySQ L
Field Descrip t io n
Name Specifies a name of the MySQL server resource.
Config File Specifies the configuration file. The default value is /etc/my.cnf.
Listen Address Specifies an IP address for MySQL server. If an IP address is not provided, the first IP address from the service is taken.
Other command line options for httpd.
mysqld
Options
Shutdown Wait
(seconds)
Specifies the number of seconds to wait for correct end of service shutdown.
T ab le C.8. NFS Clien t
Field Descrip t io n
Name
Target
This is a symbolic name of a client used to reference it in the resource tree. This is
not the same thing as the Target option.
This is the server from which you are mounting. It can be specified using a hostname, a wildcard (IP address or hostname based), or a netgroup defining a host or hosts to export to.
Options Defines a list of options for this client — for example, additional client access rights. For more information, refer to the exports (5) man page, General Options.
Allow Recover Allow recovery of the NFS client.
T ab le C.9 . NFS Exp o rt
Field
Name
Descrip t io n
Descriptive name of the resource. The NFS Export resource ensures that NFS daemons are running. It is fully reusable; typically, only one NFS Export resource is needed.
Tip
Name the NFS Export resource so it is clearly distinguished from other NFS resources.
T ab le C.10. NFS Mo u n t
Field Descrip t io n
102
Field
Name
HA Resource Paramet ers
Descrip t io n
Symbolic name for the NFS mount.
Note
This resource is required only when a cluster service is configured to be an
NFS client.
Mount point
Host
Export path
NFS version
Path to which the file system resource is mounted.
NFS server IP address or hostname.
NFS Export directory name.
NFS protocol:
NFS3 — Specifies using NFSv3 protocol. The default setting is NFS3.
NFS4 — Specifies using NFSv4 protocol.
Options Mount options. Specifies a list of mount options. If none are specified, the NFS file system is mounted -o sync. For more information, refer to the nfs(5) man page.
Force unmount If Force unmount is enabled, the cluster kills all processes using this file system when the service is stopped. Killing all processes using the file system frees up the file system. Otherwise, the unmount will fail, and the service will be restarted.
T ab le C.11. O p en LDAP
Field Descrip t io n
Name
Config File
URL List
Specifies a service name for logging and other purposes.
Specifies an absolute path to a configuration file. The default value is
/etc/openldap/slapd.conf.
The default value is ldap:///.
slapd Options Other command line options for slapd.
Shutdown Wait
(seconds)
Specifies the number of seconds to wait for correct end of service shutdown.
T ab le C.12. O racle 10g Failo ver In st an ce
Field
Instance name
(SID) of Oracle instance
Oracle user name
Oracle application home directory
Virtual hostname
(optional)
Descrip t io n
Instance name.
This is the user name of the Oracle user that the Oracle AS instance runs as.
This is the Oracle (application, not user) home directory. It is configured when you install Oracle.
Virtual Hostname matching the installation hostname of Oracle 10g. Note that during the start/stop of an oracledb resource, your hostname is changed temporarily to this hostname. Therefore, you should configure an oracledb resource as part of an exclusive service only.
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T ab le C.13. O racle DB
Field
Instance name
(SID) of Oracle instance
Oracle user name
Oracle application home directory
List of Oracle listeners
(optional, separated by spaces)
Path to lock file (optional)
Descrip t io n
Instance name.
This is the user name of the Oracle user that the Oracle instance runs as.
This is the Oracle (application, not user) home directory. It is configured when you install Oracle.
List of Oracle listeners which will be started with the database instance. Listener names are separated by whitespace. Defaults to empty which disables listeners.
Location for lockfile which will be used for checking if the Oracle should be running or not. Defaults to location under /tmp.
T ab le C.14 . O racle List en er Ag en t
Field Descrip t io n
Listener Name Listener name.
Oracle user name
This is the user name of the Oracle user that the Oracle instance runs as.
Oracle application home directory
This is the Oracle (application, not user) home directory. It is configured when you install Oracle.
T ab le C.15. Po st g reSQ L 8
Field
Name
Config File
Postmaster
User
Postmaster
Options
Startup Wait
(seconds)
Shutdown Wait
(seconds)
Descrip t io n
Specifies a service name for logging and other purposes.
Define absolute path to configuration file. The default value is
/var/lib/pgsql/data/postgresql.conf.
User who runs the database server because it cannot be run by root. The default value is postgres.
Other command line options for postmaster.
Specifies the number of seconds to wait for correct end of service startup.
Specifies the number of seconds to wait for correct end of service shutdown.
T ab le C.16 . SAP Dat ab ase
Field
SAP Database
Name
SAP executable directory
Descrip t io n
Specifies a unique SAP system identifier. For example, P01.
Specifies the fully qualified path to sapstartsrv and sapcontrol.
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HA Resource Paramet ers
Field Descrip t io n
Database type Specifies one of the following database types: Oracle, DB6, or ADA.
Oracle TNS listener name
Specifies Oracle TNS listener name.
ABAP stack is not installed, only Java stack is installed
Application
Level
Monitoring
If you do not have an ABAP stack installed in the SAP database, enable this parameter.
Activates application level monitoring.
Enable or disable automatic startup recovery.
Automatic
Startup
Recovery
Path to Java
SDK
File name of the JDBC
Driver
Path to a prestart script
Path to a poststart script
Path to a prestop script
Path to a poststop script
J2EE instance bootstrap directory
J2EE security store path
Path to Java SDK.
File name of the JDBC driver.
Path to a pre-start script.
Path to a post-start script.
Path to a pre-stop script
Path to a post-stop script
The fully qualified path the J2EE instance bootstrap directory. For example,
/usr/sap/P01/J00/j2ee/cluster/bootstrap.
The fully qualified path the J2EE security store directory. For example,
/usr/sap/P01/SYS/global/security/lib/tools.
T ab le C.17. SAP In st an ce
Field
SAP Instance
Name
SAP executable directory
Directory containing the
SAP START profile
Name of the
SAP START profile
Descrip t io n
The fully qualified SAP instance name. For example,
P01_DVEBMGS00_sapp01ci.
The fully qualified path to sapstartsrv and sapcontrol.
The fully qualified path to the SAP START profile.
Specifies name of the SAP START profile.
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Field
Number of seconds to wait before checking startup status
Enable automatic startup recovery
Path to a prestart script
Path to a poststart script
Path to a prestop script
Path to a poststop script
Descrip t io n
Specifies the number of seconds to wait before checking the startup status (do not wait for J2EE-Addin).
Enable or disable automatic startup recovery.
Path to a pre-start script.
Path to a post-start script.
Path to a pre-stop script
Path to a post-stop script
Note
Regarding
, when creating or editing a cluster service, connect a
Samba-service resource directly to the service, not to a resource within a service.
Note
Red Hat Enterprise Linux 5 does not support running Clustered Samba in an active/active configuration, in which Samba serves the same shared file system from multiple nodes. Red
Hat Enterprise Linux 5 does support running Samba in a cluster in active/passive mode, with failover from one node to the other nodes in a cluster. Note that if failover occurs, locking states are lost and active connections to Samba are severed so that the clients must reconnect.
T ab le C.18. Samb a Service
Field
Name
Workgroup
Descrip t io n
Specifies the name of the Samba server.
Specifies a Windows workgroup name or Windows NT domain of the Samba service.
T ab le C.19 . Scrip t
Field
Name
Full path to script file
Descrip t io n
Specifies a name for the custom user script. The script resource allows a standard LSB-compliant init script to be used to start a clustered service.
Enter the path where this custom script is located (for example,
/etc/init.d/userscript).
T ab le C.20. Service
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HA Resource Paramet ers
T ab le C.20. Service
Field Descrip t io n
Service name Name of service. This defines a collection of resources, known as a resource group or cluster service.
Automatically start this service
If enabled, this service (or resource group) is started automatically after the cluster forms a quorum. If this parameter is disabled, this service is not started automatically after the cluster forms a quorum; the service is put into the
disabled state.
Run exclusive If enabled, this service (resource group) can only be relocated to run on another node exclusively; that is, to run on a node that has no other services running on it. If no nodes are available for a service to run exclusively, the service is not restarted after a failure. Additionally, other services do not automatically relocate to a node running this service as Run exclusive. You can override this option by manual start or relocate operations.
Failover
Domain
Defines lists of cluster members to try in the event that a service fails. For
information on configuring a failover domain with Conga, refer to Section 3.7,
“ Configuring a Failover Domain” . For information on configuring a failover
domain with system-config-cluster, refer to Section 5.6, “ Configuring a
Recovery policy
Recovery policy provides the following options:
Disable — Disables the resource group if any component fails.
Relocate — Tries to restart service in another node; that is, it does not try to restart in the current node.
Restart — Tries to restart failed parts of this service locally (in the current node) before trying to relocate (default) to service to another node.
Restart-Disable — (Red Hat Enterprise Linux release 5.6 and later) The service will be restarted in place if it fails. However, if restarting the service fails the service will be disabled instead of being moved to another host in the cluster.
T ab le C.21. Syb ase ASE Failo ver In st an ce
Field Descrip t io n
Instance Name Specifies the instance name of the Sybase ASE resource.
ASE server name
The ASE server name that is configured for the HA service.
The home directory of Sybase products.
SYBASE home directory
Login file The full path of login file that contains the login-password pair.
The full path of the interfaces file that is used to start/access the ASE server.
The directory name under sybase_home where ASE products are installed.
Interfaces file
SYBASE_ASE directory name
SYBASE_OCS directory name
Sybase user
Deep probe timeout
The directory name under sybase_home where OCS products are installed. For example, ASE-15_0.
The user who can run ASE server.
The maximum seconds to wait for the response of ASE server before determining that the server had no response while running deep probe.
T ab le C.22. T o mcat 5
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Field Descrip t io n
Name
Config File
Specifies a service name for logging and other purposes.
Specifies the absolute path to the configuration file. The default value is
/etc/tomcat5/tomcat5.conf.
Tomcat User
Catalina
Options
User who runs the Tomcat server. The default value is tomcat.
Other command line options for Catalina.
Catalina Base Catalina base directory (differs for each service) The default value is
/usr/share/tomcat5.
Shutdown Wait
(seconds)
Specifies the number of seconds to wait for correct end of service shutdown. The default value is 30.
Important
Regarding
Table C.23, “ Virtual Machine” , when you configure your cluster with virtual
machine resources, you should use the rgmanager tools to start and stop the virtual machines. Using xm or virsh to start the machine can result in the virtual machine running in more than one place, which can cause data corruption in the virtual machine. For information on configuring your system to reduce the chances of administrators accidentally "double-
starting" virtual machines by using both cluster and non-cluster tools, refer to Section 2.12,
“ Configuring Virtual Machines in a Clustered Environment” .
Note
Virtual machine resources are configured differently than other cluster resources; they are configured as services. To configure a virtual machine resource with lu ci, at the detailed menu for the cluster (below the clu st ers menu), click Services, then click Ad d a Virt u al
Mach in e Service. You can then enter the virtual machine resource parameters. For
T ab le C.23. Virt u al Mach in e
Field
Virtual machine name
Path to VM configuration files
Descrip t io n
Specifies the name of the virtual machine.
A colon-delimited path specification that xm create searches for the virtual machine configuration file. For example:
/etc/xen:/guests/config_files:/var/xen/configs
Important
The path should never directly point to a virtual machine configuration file.
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HA Resource Paramet ers
Field
VM Migration
Mapping
Descrip t io n
Specifies an alternate interface for migration. You can specify this when, for example, the network address used for virtual machine migration on a node differs from the address of the node used for cluster communication.
Specifying the following indicates that when you migrate a virtual machine from
member to member2, you actually migrate to target2. Similarly, when you migrate from member2 to member, you migrate using target.
member:target,member2:target2
Migration type Specifies a migration type of live or pause. The default setting is live.
Hypervisor Hypervisor URI (automatic, KVM, or Xen)
Automatically start this service
If enabled, this virtual machine is started automatically after the cluster forms a quorum. If this parameter is disabled, this virtual machine service is not started automatically after the cluster forms a quorum; the virtual machine is put into the
disabled state.
Run exclusive If enabled, this virtual machine can only be relocated to run on another node exclusively; that is, to run on a node that has no other virtual machines running on it. If no nodes are available for a virtual machine to run exclusively, the virtual machine is not restarted after a failure. Additionally, other virtual machines do not automatically relocate to a node running this virtual machine as Run
exclusive. You can override this option by manual start or relocate operations.
Defines lists of cluster members to try in the event that a virtual machine fails.
Failover
Domain
Recovery policy
Recovery policy provides the following options:
Disable — Disables the virtual machine if it fails.
Relocate — Tries to restart the virtual machine in another node; that is, it does not try to restart in the current node.
Restart — Tries to restart the virtual machine locally (in the current node) before trying to relocate (default) to virtual machine to another node.
Restart-Disable — (Red Hat Enterprise Linux Release 5.6 and later) The service will be restarted in place if it fails. However, if restarting the service fails the service will be disabled instead of being moved to another host in the cluster.
Maximum number of restart failures before relocating
Length of time in seconds after which to forget a restart
Maximum number of restarts for an independent subtree before giving up.
Amount of time before a failure is forgotten for an independent subtree.
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HA Resource Behavior
This appendix describes common behavior of HA resources. It is meant to provide ancillary information that may be helpful in configuring HA services. You can configure the parameters with
Lu ci, system-config-cluster, or by editing etc/cluster/cluster.conf. For descriptions of
HA resource parameters, refer to Appendix C, HA Resource Parameters . To understand resource
agents in more detail you can view them in /usr/share/cluster of any cluster node.
Note
To fully comprehend the information in this appendix, you may require detailed understanding of resource agents and the cluster configuration file, /etc/cluster/cluster.conf.
An HA service is a group of cluster resources configured into a coherent entity that provides specialized services to clients. An HA service is represented as a resource tree in the cluster configuration file, /etc/cluster/cluster.conf (in each cluster node). In the cluster configuration file, each resource tree is an XML representation that specifies each resource, its attributes, and its relationship among other resources in the resource tree (parent, child, and sibling relationships).
Note
Because an HA service consists of resources organized into a hierarchical tree, a service is sometimes referred to as a resource tree or resource group. Both phrases are synonymous with
HA service.
At the root of each resource tree is a special type of resource — a service resource. Other types of resources comprise the rest of a service, determining its characteristics. Configuring an HA service consists of creating a service resource, creating subordinate cluster resources, and organizing them into a coherent entity that conforms to hierarchical restrictions of the service.
This appendix consists of the following sections:
Section D.1, “ Parent, Child, and Sibling Relationships Among Resources”
Section D.2, “ Sibling Start Ordering and Resource Child Ordering”
Section D.3, “ Inheritance, the <resources> Block, and Reusing Resources”
Section D.4, “ Failure Recovery and Independent Subtrees”
Section D.5, “ Debugging and Testing Services and Resource Ordering”
Note
The sections that follow present examples from the cluster configuration file,
/etc/cluster/cluster.conf, for illustration purposes only.
D.1. Parent , Child, and Sibling Relat ionships Among Resources
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HA Resource Behavior
A cluster service is an integrated entity that runs under the control of rgmanager. All resources in a service run on the same node. From the perspective of rgmanager, a cluster service is one entity that can be started, stopped, or relocated. Within a cluster service, however, the hierarchy of the resources determines the order in which each resource is started and stopped.The hierarchical levels consist of parent, child, and sibling.
the example, the relationships among the resources are as follows:
fs:myfs (<fs name="myfs" ...>) and ip:10.1.1.2 (<ip address="10.1.1.2 .../>) are siblings.
fs:myfs (<fs name="myfs" ...>) is the parent of script:script_child (<script name="script_child"/>).
script:script_child (<script name="script_child"/>) is the child of fs:myfs (<fs name="myfs" ...>).
Examp le D.1. Reso u rce Hierarch y o f Service f o o
<service name="foo" ...>
<fs name="myfs" ...>
<script name="script_child"/>
</fs>
<ip address="10.1.1.2" .../>
</service>
The following rules apply to parent/child relationships in a resource tree:
Parents are started before children.
Children must all stop cleanly before a parent may be stopped.
For a resource to be considered in good health, all its children must be in good health.
D.2. Sibling St art Ordering and Resource Child Ordering
The Service resource determines the start order and the stop order of a child resource according to whether it designates a child-type attribute for a child resource as follows:
Designates child-type attribute (typed child resource) — If the Service resource designates a childtype attribute for a child resource, the child resource is typed. The child-type attribute explicitly determines the start and the stop order of the child resource.
Does not designate child-type attribute (non-typed child resource) — If the Service resource does not
designate a child-type attribute for a child resource, the child resource is non-typed. The Service resource does not explicitly control the starting order and stopping order of a non-typed child resource. However, a non-typed child resource is started and stopped according to its order in
/etc/cluster/cluster.conf In addition, non-typed child resources are started after all typed child resources have started and are stopped before any typed child resources have stopped.
Note
The only resource to implement defined child resource type ordering is the Service resource.
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For more information about typed child resource start and stop ordering, refer to Section D.2.1,
“ Typed Child Resource Start and Stop Ordering” . For more information about non-typed child
resource start and stop ordering, refer to Section D.2.2, “ Non-typed Child Resource Start and Stop
D.2.1. T yped Child Resource St art and St op Ordering
For a typed child resource, the type attribute for the child resource defines the start order and the stop order of each resource type with a number ranging from 1 to 100; one value for start, and one value
for stop. The lower the number, the earlier a resource type starts or stops. For example, Table D.1,
“ Child Resource Type Start and Stop Order” shows the start and stop values for each resource type;
Example D.2, “ Resource Start and Stop Values: Excerpt from Service Resource Agent, service.sh”
shows the start and stop values as they appear in the Service resource agent, service.sh. For the
Service resource, all LVM children are started first, followed by all File System children, followed by all Script children, and so forth.
T ab le D.1. Ch ild Reso u rce T yp e St art an d St o p O rd er
Reso u rce
LVM
File System
GFS File System
NFS Mount
NFS Export
NFS Client
IP Address
Samba
Script
Ch ild T yp e lvm fs clusterfs netfs nfsexport nfsclient ip smb script
St art - o rd er Valu e
7
8
5
6
3
4
1
2
9
St o p - o rd er Valu e
2
3
5
4
7
6
9
8
1
Examp le D.2. Reso u rce St art an d St o p Valu es: Excerp t f ro m Service Reso u rce Ag en t , service.sh
<special tag="rgmanager">
<attributes root="1" maxinstances="1"/>
<child type="lvm" start="1" stop="9"/>
<child type="fs" start="2" stop="8"/>
<child type="clusterfs" start="3" stop="7"/>
<child type="netfs" start="4" stop="6"/>
<child type="nfsexport" start="5" stop="5"/>
<child type="nfsclient" start="6" stop="4"/>
<child type="ip" start="7" stop="2"/>
<child type="smb" start="8" stop="3"/>
<child type="script" start="9" stop="1"/>
</special>
Ordering within a resource type is preserved as it exists in the cluster configuration file,
/etc/cluster/cluster.conf. For example, consider the starting order and stopping order of the typed child resources in
Example D.3, “ Ordering Within a Resource Type”
.
Examp le D.3. O rd erin g Wit h in a Reso u rce T yp e
<service name="foo">
<script name="1" .../>
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HA Resource Behavior
<lvm name="1" .../>
<ip address="10.1.1.1" .../>
<fs name="1" .../>
<lvm name="2" .../>
</service>
T ype d Child Re so urce St art ing Orde r
In
Example D.3, “ Ordering Within a Resource Type”
, the resources are started in the following order:
1. lvm:1 — This is an LVM resource. All LVM resources are started first. lvm:1 (<lvm
name="1" .../>) is the first LVM resource started among LVM resources because it is the first LVM resource listed in the Service foo portion of /etc/cluster/cluster.conf.
2. lvm:2 — This is an LVM resource. All LVM resources are started first. lvm:2 (<lvm
name="2" .../>) is started after lvm:1 because it is listed after lvm:1 in the Service foo portion of /etc/cluster/cluster.conf.
3. fs:1 — This is a File System resource. If there were other File System resources in Service
foo, they would start in the order listed in the Service foo portion of
/etc/cluster/cluster.conf.
4. ip:10.1.1.1 — This is an IP Address resource. If there were other IP Address resources in
Service foo, they would start in the order listed in the Service foo portion of
/etc/cluster/cluster.conf.
5. script:1 — This is a Script resource. If there were other Script resources in Service foo, they would start in the order listed in the Service foo portion of /etc/cluster/cluster.conf.
T ype d Child Re so urce St o pping Orde r
In
Example D.3, “ Ordering Within a Resource Type”
, the resources are stopped in the following order:
1. script:1 — This is a Script resource. If there were other Script resources in Service foo, they would stop in the reverse order listed in the Service foo portion of
/etc/cluster/cluster.conf.
2. ip:10.1.1.1 — This is an IP Address resource. If there were other IP Address resources in
Service foo, they would stop in the reverse order listed in the Service foo portion of
/etc/cluster/cluster.conf.
3. fs:1 — This is a File System resource. If there were other File System resources in Service
foo, they would stop in the reverse order listed in the Service foo portion of
/etc/cluster/cluster.conf.
4. lvm:2 — This is an LVM resource. All LVM resources are stopped last. lvm:2 (<lvm
name="2" .../>) is stopped before lvm:1; resources within a group of a resource type are stopped in the reverse order listed in the Service foo portion of
/etc/cluster/cluster.conf.
5. lvm:1 — This is an LVM resource. All LVM resources are stopped last. lvm:1 (<lvm
name="1" .../>) is stopped after lvm:2; resources within a group of a resource type are stopped in the reverse order listed in the Service foo portion of
/etc/cluster/cluster.conf.
D.2.2. Non-t yped Child Resource St art and St op Ordering
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D.2.2. Non-t yped Child Resource St art and St op Ordering
Additional considerations are required for non-typed child resources. For a non-typed child resource, starting order and stopping order are not explicitly specified by the Service resource.
Instead, starting order and stopping order are determined according to the order of the child resource in /etc/cluster/cluster.conf. Additionally, non-typed child resources are started after all typed child resources and stopped before any typed child resources.
For example, consider the starting order and stopping order of the non-typed child resources in
Example D.4, “ Non-typed and Typed Child Resource in a Service”
.
Examp le D.4 . No n - t yp ed an d T yp ed Ch ild Reso u rce in a Service
<service name="foo">
<script name="1" .../>
<nontypedresource name="foo"/>
<lvm name="1" .../>
<nontypedresourcetwo name="bar"/>
<ip address="10.1.1.1" .../>
<fs name="1" .../>
<lvm name="2" .../>
</service>
No n-t ype d Child Re so urce St art ing Orde r
In
Example D.4, “ Non-typed and Typed Child Resource in a Service” , the child resources are started
in the following order:
1. lvm:1 — This is an LVM resource. All LVM resources are started first. lvm:1 (<lvm
name="1" .../>) is the first LVM resource started among LVM resources because it is the first LVM resource listed in the Service foo portion of /etc/cluster/cluster.conf.
2. lvm:2 — This is an LVM resource. All LVM resources are started first. lvm:2 (<lvm
name="2" .../>) is started after lvm:1 because it is listed after lvm:1 in the Service foo portion of /etc/cluster/cluster.conf.
3. fs:1 — This is a File System resource. If there were other File System resources in Service
foo, they would start in the order listed in the Service foo portion of
/etc/cluster/cluster.conf.
4. ip:10.1.1.1 — This is an IP Address resource. If there were other IP Address resources in
Service foo, they would start in the order listed in the Service foo portion of
/etc/cluster/cluster.conf.
5. script:1 — This is a Script resource. If there were other Script resources in Service foo, they would start in the order listed in the Service foo portion of /etc/cluster/cluster.conf.
6. nontypedresource:foo — This is a non-typed resource. Because it is a non-typed resource, it is started after the typed resources start. In addition, its order in the Service resource is before the other non-typed resource, nontypedresourcetwo:bar; therefore, it is started before nontypedresourcetwo:bar. (Non-typed resources are started in the order that they appear in the Service resource.)
7. nontypedresourcetwo:bar — This is a non-typed resource. Because it is a non-typed resource, it is started after the typed resources start. In addition, its order in the Service resource is after the other non-typed resource, nontypedresource:foo; therefore, it is
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HA Resource Behavior started after nontypedresource:foo. (Non-typed resources are started in the order that they appear in the Service resource.)
No n-t ype d Child Re so urce St o pping Orde r
In
Example D.4, “ Non-typed and Typed Child Resource in a Service” , the child resources are stopped
in the following order:
1. nontypedresourcetwo:bar — This is a non-typed resource. Because it is a non-typed resource, it is stopped before the typed resources are stopped. In addition, its order in the
Service resource is after the other non-typed resource, nontypedresource:foo; therefore, it is stopped before nontypedresource:foo. (Non-typed resources are stopped in the reverse order that they appear in the Service resource.)
2. nontypedresource:foo — This is a non-typed resource. Because it is a non-typed resource, it is stopped before the typed resources are stopped. In addition, its order in the
Service resource is before the other non-typed resource, nontypedresourcetwo:bar; therefore, it is stopped after nontypedresourcetwo:bar. (Non-typed resources are stopped in the reverse order that they appear in the Service resource.)
3. script:1 — This is a Script resource. If there were other Script resources in Service foo, they would stop in the reverse order listed in the Service foo portion of
/etc/cluster/cluster.conf.
4. ip:10.1.1.1 — This is an IP Address resource. If there were other IP Address resources in
Service foo, they would stop in the reverse order listed in the Service foo portion of
/etc/cluster/cluster.conf.
5. fs:1 — This is a File System resource. If there were other File System resources in Service
foo, they would stop in the reverse order listed in the Service foo portion of
/etc/cluster/cluster.conf.
6. lvm:2 — This is an LVM resource. All LVM resources are stopped last. lvm:2 (<lvm
name="2" .../>) is stopped before lvm:1; resources within a group of a resource type are stopped in the reverse order listed in the Service foo portion of
/etc/cluster/cluster.conf.
7. lvm:1 — This is an LVM resource. All LVM resources are stopped last. lvm:1 (<lvm
name="1" .../>) is stopped after lvm:2; resources within a group of a resource type are stopped in the reverse order listed in the Service foo portion of
/etc/cluster/cluster.conf.
D.3. Inherit ance, t he <resources> Block, and Reusing Resources
Some resources benefit by inheriting values from a parent resource; that is commonly the case in an
NFS service. Example D.5, “ NFS Service Set Up for Resource Reuse and Inheritance”
shows a typical NFS service configuration, set up for resource reuse and inheritance.
Examp le D.5. NFS Service Set Up f o r Reso u rce Reu se an d In h erit an ce
<resources>
<nfsclient name="bob" target="bob.example.com" options="rw,no_root_squash"/>
<nfsclient name="jim" target="jim.example.com" options="rw,no_root_squash"/>
<nfsexport name="exports"/>
</resources>
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<service name="foo">
<fs name="1" mountpoint="/mnt/foo" device="/dev/sdb1" fsid="12344">
<nfsexport ref="exports"> <!-- nfsexport's path and fsid
attributes are inherited from the mountpoint and fsid
attribute of the parent fs resource -->
<nfsclient ref="bob"/> <!-- nfsclient's path is inherited
from the mountpoint and the fsid is added to the options
string during export -->
<nfsclient ref="jim"/ >
</nfsexport>
</fs>
<fs name="2" mountpoint="/mnt/bar" device="/dev/sdb2" fsid="12345">
<nfsexport ref="exports">
<nfsclient ref="bob"/> <!-- Because all of the critical
data for this resource is either defined in the resources block
or inherited, we can reference it again! -->
<nfsclient ref="jim"/>
</nfsexport>
</fs>
<ip address="10.2.13.20"/>
</service>
If the service were flat (that is, with no parent/child relationships), it would need to be configured as follows:
The service would need four nfsclient resources — one per file system (a total of two for file systems), and one per target machine (a total of two for target machines).
The service would need to specify export path and file system ID to each nfsclient, which introduces chances for errors in the configuration.
In
Example D.5, “ NFS Service Set Up for Resource Reuse and Inheritance” however, the NFS client
resources nfsclient:bob and nfsclient:jim are defined once; likewise, the NFS export resource
nfsexport:exports is defined once. All the attributes needed by the resources are inherited from parent resources. Because the inherited attributes are dynamic (and do not conflict with one another), it is possible to reuse those resources — which is why they are defined in the resources block. It may not be practical to configure some resources in multiple places. For example, configuring a file system resource in multiple places can result in mounting one file system on two nodes, therefore causing problems.
D.4 . Failure Recovery and Independent Subt rees
In most enterprise environments, the normal course of action for failure recovery of a service is to
action is to restart (or relocate or disable, according to the service recovery policy) the service.
However, in some circumstances certain parts of a service may be considered non-critical; it may be necessary to restart only part of the service in place before attempting normal recovery. To accomplish that, you can use the __independent_subtree attribute. For example, in
Example D.7, “ Service foo Failure Recovery with __independent_subtree Attribute”
, the
__independent_subtree attribute is used to accomplish the following actions:
If script:script_one fails, restart script:script_two and script:script_one.
If script:script_two fails, restart just script:script_two.
If script:script_three fails, restart script:script_one, script:script_two, and script:script_three.
If script:script_four fails, restart the whole service.
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HA Resource Behavior
Examp le D.6 . Service foo No rmal Failu re Reco very
<service name="foo">
<script name="script_one" ...>
<script name="script_two" .../>
</script>
<script name="script_three" .../>
</service>
Examp le D.7. Service foo Failu re Reco very wit h __independent_subtree At t rib u t e
<service name="foo">
<script name="script_one" __independent_subtree="1" ...>
<script name="script_two" __independent_subtree="1" .../>
<script name="script_three" .../>
</script>
<script name="script_four" .../>
</service>
In some circumstances, if a component of a service fails you may want to disable only that component without disabling the entire service, to avoid affecting other services the use other components of that service. As of the Red Hat Enterprise Linux 5.6 release, you can accomplish that by using the __independent_subtree="2" attribute, which designates the independent subtree as non-critical.
Note
You may only use the non-critical flag on singly-referenced resources. The non-critical flag works with all resources at all levels of the resource tree, but should not be used at the top level when defining services or virtual machines.
As of the Red Hat Enterprise Linux 5.6 release, you can set maximum restart and restart expirations on a per-node basis in the resource tree for independent subtrees. To set these thresholds, you can use the following attributes:
__max_restarts configures the maximum number of tolerated restarts prior to giving up.
__restart_expire_time configures the amount of time, in seconds, after which a restart is no longer attempted.
D.5. Debugging and T est ing Services and Resource Ordering
You can debug and test services and resource ordering with the rg_test utility. rg_test is a command-line utility that is run from a shell or a terminal (it is not available in Co n g a or system-
config-cluster.) Table D.2, “ rg_test Utility Summary”
summarizes the actions and syntax for the rg_test utility.
T ab le D.2. rg_test Ut ilit y Su mmary
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Act io n
Display the resource rules that rg_test understand s.
Test a configuratio n (and
/usr/share/c luster) for errors or redundant resource agents.
Display the start and stop ordering of a service.
Syn t ax rg_test rules rg_test test /etc/cluster/cluster.conf
Display start order: rg_test noop /etc/cluster/cluster.conf start service servicename
Display stop order: rg_test noop /etc/cluster/cluster.conf stop service servicename
Explicitly start or stop a service.
Important
Only do this on one node, and always disable the service in rgmanager first.
Start a service: rg_test test /etc/cluster/cluster.conf start service servicename
Stop a service:
rg_test test /etc/cluster/cluster.conf stop service servicename
Calculate and display the resource tree delta between two cluster.conf
files.
rg_test delta cluster.conf file 1 cluster.conf file 2
For example: rg_test delta /etc/cluster/cluster.conf.bak
/etc/cluster/cluster.conf
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Clust er Service Resource Check and Failover T imeout
Cluster Service Resource Check and Failover Timeout
This appendix describes how rgmanager monitors the status of cluster resources, and how to modify the status check interval. The appendix also describes the __enforce_timeouts service parameter, which indicates that a timeout for an operation should cause a service to fail.
Note
To fully comprehend the information in this appendix, you may require detailed understanding of resource agents and the cluster configuration file, /etc/cluster/cluster.conf. For a comprehensive list and description of cluster.conf elements and attributes, refer to the cluster schema at /usr/share/system-config-cluster/misc/cluster.ng, and the annotated schema at /usr/share/doc/system-config-cluster-
X.Y.ZZ/cluster_conf.html (for example /usr/share/doc/system-config-
cluster-1.0.57/cluster_conf.html).
E.1. Modifying t he Resource St at us Check Int erval
rgmanager checks the status of individual resources, not whole services. (This is a change from
clumanager on Red Hat Enterprise Linux 3, which periodically checked the status of the whole service.) Every 10 seconds, rgmanager scans the resource tree, looking for resources that have passed their "status check" interval.
Each resource agent specifies the amount of time between periodic status checks. Each resource utilizes these timeout values unless explicitly overridden in the cluster.conf file using the special
<action> tag:
<action name="status" depth="*" interval="10" />
This tag is a special child of the resource itself in the cluster.conf file. For example, if you had a file system resource for which you wanted to override the status check interval you could specify the file system resource in the cluster.conf file as follows:
<fs name="test" device="/dev/sdb3">
<action name="status" depth="*" interval="10" />
<nfsexport...>
</nfsexport>
</fs>
Some agents provide multiple "depths" of checking. For example, a normal file system status check
(depth 0) checks whether the file system is mounted in the correct place. A more intensive check is depth 10, which checks whether you can read a file from the file system. A status check of depth 20 checks whether you can write to the file system. In the example given here, the depth is set to *, which indicates that these values should be used for all depths. The result is that the test file system is checked at the highest-defined depth provided by the resource-agent (in this case, 20) every 10 seconds.
E.2. Enforcing Resource T imeout s
There is no timeout for starting, stopping, or failing over resources. Some resources take an
119
Red Hat Ent erprise Linux 5 Clust er Administ rat ion indeterminately long amount of time to start or stop. Unfortunately, a failure to stop (including a timeout) renders the service inoperable (failed state). You can, if desired, turn on timeout enforcement on each resource in a service individually by adding __enforce_timeouts="1" to the reference in the cluster.conf file.
The following example shows a cluster service that has been configured with the
__enforce_timeouts attribute set for the netfs resource. With this attribute set, then if it takes more than 30 seconds to unmount the NFS file system during a recovery process the operation will time out, causing the service to enter the failed state.
</screen>
<rm>
<failoverdomains/>
<resources>
<netfs export="/nfstest" force_unmount="1" fstype="nfs" host="10.65.48.65"
mountpoint="/data/nfstest" name="nfstest_data" options="rw,sync,soft"/>
</resources>
<service autostart="1" exclusive="0" name="nfs_client_test" recovery="relocate">
<netfs ref="nfstest_data" __enforce_timeouts="1"/>
</service>
</rm>
E.3. Changing Consensus T imeout
The consensus timeout specifies the time (in milliseconds) to wait for consensus to be achieved before starting a new round of membership configuration.
When consensus is calculated automatically, the following rules will be used:
If configuring a cluster of 2 or less nodes, consensus will be (token * 0.2) , with a maximum of 2000 milliseconds and a minimum of 200 milliseconds.
If configuring a cluster of 3 or more nodes, consensus will be (token + 2000 milliseconds)
If you let cman configure your consensus timeout in this fashion, realize that moving from 2 to 3 (or more) nodes will require a cluster restart, since the consensus timeout will need to change to the larger value based on the token timeout.
When configuring a 2-member cluster with the ultimate intention of adding more nodes at a later time, you must adjust the consensus timeout so that you do not have to restart the cluster to add the new nodes. To do this, you can edit the cluster.conf as follows:
<totem token="X" consensus="X + 2000" />
Note that the configuration parser does not calculate X + 2000 automatically. An integer value must be used rather than an equation.
The advantage of the optimized consensus timeout for 2 node clusters is that overall failover time is reduced for the 2 node case since consensus is not a function of the token timeout.
120
Clust er Service Resource Check and Failover T imeout
Note
For two node auto-detection in cman, the number of physical nodes matters and not the presence of the two_node=1 directive in cluster.conf.
121
Red Hat Ent erprise Linux 5 Clust er Administ rat ion
High Availabilty LVM (HA-LVM)
The Red Hat High Availability Add-On provides support for high availability LVM volumes (HA-LVM) in a failover configuration. This is distinct from active/active configurations enabled by the Clustered
Logical Volume Manager (CLVM), which is a set of clustering extensions to LVM that allow a cluster of computers to manage shared storage.
When to use CLVM or HA-LVM should be based on the needs of the applications or services being deployed.
If the applications are cluster-aware and have been tuned to run simultaneously on multiple machines at a time, then CLVM should be used. Specifically, if more than one node of your cluster will require access to your storage which is then shared among the active nodes, then you must use CLVM. CLVM allows a user to configure logical volumes on shared storage by locking access to physical storage while a logical volume is being configured, and uses clustered locking services to manage the shared storage. For information on CLVM, and on LVM configuration in general, refer to Logical Volume Manager Administration.
If the applications run optimally in active/passive (failover) configurations where only a single node that accesses the storage is active at any one time, you should use High Availability Logical
Volume Management agents (HA-LVM).
Most applications will run better in an active/passive configuration, as they are not designed or optimized to run concurrently with other instances. Choosing to run an application that is not clusteraware on clustered logical volumes may result in degraded performance if the logical volume is mirrored. This is because there is cluster communication overhead for the logical volumes themselves in these instances. A cluster-aware application must be able to achieve performance gains above the performance losses introduced by cluster file systems and cluster-aware logical volumes. This is achievable for some applications and workloads more easily than others.
Determining what the requirements of the cluster are and whether the extra effort toward optimizing for an active/active cluster will pay dividends is the way to choose between the two LVM variants. Most users will achieve the best HA results from using HA-LVM.
HA-LVM and CLVM are similar in the fact that they prevent corruption of LVM metadata and its logical volumes, which could otherwise occur if multiple machines where allowed to make overlapping changes. HA-LVM imposes the restriction that a logical volume can only be activated exclusively; that is, active on only one machine at a time. This means that only local (non-clustered) implementations of the storage drivers are used. Avoiding the cluster coordination overhead in this way increases performance. CLVM does not impose these restrictions - a user is free to activate a logical volume on all machines in a cluster; this forces the use of cluster-aware storage drivers, which allow for clusteraware file systems and applications to be put on top.
HA-LVM can be setup to use one of two methods for achieving its mandate of exclusive logical volume activation.
The preferred method uses CLVM, but it will only ever activate the logical volumes exclusively.
This has the advantage of easier setup and better prevention of administrative mistakes (like removing a logical volume that is in use). In order to use CLVM, the High Availability Add-On and
Resilient Storage Add-On software, including the clvmd daemon, must be running.
The procedure for configuring HA-LVM using this method is described in Section F.1,
“ Configuring HA-LVM Failover with CLVM (preferred, Red Hat Enterprise Linux 5.6 and later)”
.
The second method uses local machine locking and LVM "tags". This method has the advantage of not requiring any LVM cluster packages; however, there are more steps involved in setting it up and it does not prevent an administrator from mistakenly removing a logical volume from a node in the cluster where it is not active. The procedure for configuring HA-LVM using this method is
122
High Availabilt y LVM (HA- LVM)
described in Section F.2, “ Configuring HA-LVM Failover with Tagging” .
F.1. Configuring HA-LVM Failover wit h CLVM (preferred, Red Hat
Ent erprise Linux 5.6 and lat er)
To set up HA-LVM failover (using the preferred CLVM variant), perform the following steps:
1. Ensure that your system is configured to support CLVM, which requires the following:
The High Availability Add-On and Resilient Storage Add-On are installed, including the the cmirror package if the CLVM logical volumes are to be mirrored.
The locking_type parameter in the global section of the /etc/lvm/lvm.conf file is set to the value '3'.
The High Availability Add-On and Resilient Storage Add-On software, including the clvmd daemon, must be running. For CLVM mirroring, the cmirrord service must be started as well.
2. Create the logical volume and file system using standard LVM and file system commands, as in the following example.
# pvcreate /dev/sd[cde]1
# vgcreate -cy shared_vg /dev/sd[cde]1
# lvcreate -L 10G -n ha_lv shared_vg
# mkfs.ext3 /dev/shared_vg/ha_lv
# lvchange -an shared_vg/ha_lv
For information on creating LVM logical volumes, refer to Logical Volume Manager
Administration.
3. Edit the /etc/cluster/cluster.conf file to include the newly created logical volume as a resource in one of your services. Alternately, you can use Co n g a or the ccs command to configure LVM and file system resources for the cluster. The following is a sample resource manager section from the /etc/cluster/cluster.conf file that configures a CLVM logical volume as a cluster resource:
<rm>
<failoverdomains>
<failoverdomain name="FD" ordered="1" restricted="0">
<failoverdomainnode name="neo-01" priority="1"/>
<failoverdomainnode name="neo-02" priority="2"/>
</failoverdomain>
</failoverdomains>
<resources>
<lvm name="lvm" vg_name="shared_vg" lv_name="ha-lv"/>
<fs name="FS" device="/dev/shared_vg/ha-lv" force_fsck="0" force_unmount="1" fsid="64050" fstype="ext3" mountpoint="/mnt" options="" self_fence="0"/>
</resources>
<service autostart="1" domain="FD" name="serv" recovery="relocate">
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Red Hat Ent erprise Linux 5 Clust er Administ rat ion
<lvm ref="lvm"/>
<fs ref="FS"/>
</service>
</rm>
F.2. Configuring HA-LVM Failover wit h T agging
To set up HA-LVM failover by using tags in the /etc/lvm/lvm.conf file, perform the following steps:
1. Ensure that the locking_type parameter in the global section of the /etc/lvm/lvm.conf file is set to the value '1'.
2. Create the logical volume and file system using standard LVM and file system commands, as in the following example.
# pvcreate /dev/sd[cde]1
# vgcreate shared_vg /dev/sd[cde]1
# lvcreate -L 10G -n ha_lv shared_vg
# mkfs.ext3 /dev/shared_vg/ha_lv
For information on creating LVM logical volumes, refer to Logical Volume Manager
Administration.
3. Edit the /etc/cluster/cluster.conf file to include the newly created logical volume as a resource in one of your services. Alternately, you can use Co n g a or the ccs command to configure LVM and file system resources for the cluster. The following is a sample resource manager section from the /etc/cluster/cluster.conf file that configures a CLVM logical volume as a cluster resource:
<rm>
<failoverdomains>
<failoverdomain name="FD" ordered="1" restricted="0">
<failoverdomainnode name="neo-01" priority="1"/>
<failoverdomainnode name="neo-02" priority="2"/>
</failoverdomain>
</failoverdomains>
<resources>
<lvm name="lvm" vg_name="shared_vg" lv_name="ha_lv"/>
<fs name="FS" device="/dev/shared_vg/ha_lv" force_fsck="0" force_unmount="1" fsid="64050" fstype="ext3" mountpoint="/mnt" options="" self_fence="0"/>
</resources>
<service autostart="1" domain="FD" name="serv" recovery="relocate">
<lvm ref="lvm"/>
<fs ref="FS"/>
</service>
</rm>
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High Availabilt y LVM (HA- LVM)
Note
If there are multiple logical volumes in the volume group, then the logical volume name
( lv_name) in the lvm resource should be left blank or unspecified. Also note that in an
HA-LVM configuration, a volume group may be used by only a single service.
4. Edit the volume_list field in the /etc/lvm/lvm.conf file. Include the name of your root volume group and your hostname as listed in the /etc/cluster/cluster.conf file preceded by @. The hostname to include here is the machine on which you are editing the
lvm.conf file, not any remote hostname. Note that this string MUST match the node name given in the cluster.conf file. Below is a sample entry from the /etc/lvm/lvm.conf file: volume_list = [ "VolGroup00", "@neo-01" ]
This tag will be used to activate shared VGs or LVs. DO NOT include the names of any volume groups that are to be shared using HA-LVM.
5. Update the initrd device on all your cluster nodes:
# mkinitrd -f /boot/initrd-$(uname -r).img $(uname -r)
6. Reboot all nodes to ensure the correct initrd device is in use.
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Red Hat Ent erprise Linux 5 Clust er Administ rat ion
Upgrading A Red Hat Cluster from RHEL 4 to RHEL 5
This appendix provides a procedure for upgrading a Red Hat cluster from RHEL 4 to RHEL 5. The procedure includes changes required for Red Hat GFS and CLVM, also. For more information about
Red Hat GFS, refer to Global File System: Configuration and Administration. For more information about
LVM for clusters, refer to LVM Administrator's Guide: Configuration and Administration.
Upgrading a Red Hat Cluster from RHEL 4 to RHEL 5 consists of stopping the cluster, converting the configuration from a GULM cluster to a CMAN cluster (only for clusters configured with the GULM cluster manager/lock manager), adding node IDs, and updating RHEL and cluster software. To upgrade a Red Hat Cluster from RHEL 4 to RHEL 5, follow these steps:
1. Stop client access to cluster high-availability services.
2. At each cluster node, stop the cluster software as follows: a. Stop all high-availability services.
b. Run service rgmanager stop.
c. Run service gfs stop, if you are using Red Hat GFS.
d. Run service clvmd stop, if CLVM has been used to create clustered volumes.
Note
If clvmd is already stopped, an error message is displayed:
# service clvmd stop
Stopping clvm:
[FAILED]
The error message is the expected result when running service clvmd stop after clvmd has stopped.
126 e. Depending on the type of cluster manager (either CMAN or GULM), run the following command or commands:
CMAN — Run service fenced stop; service cman stop.
GULM — Run service lock_gulmd stop.
f. Run service ccsd stop.
3. Disable cluster software from starting during reboot. At each node, run /sbin/chkconfig as follows:
# chkconfig --level 2345 rgmanager off
# chkconfig --level 2345 gfs off
# chkconfig --level 2345 clvmd off
# chkconfig --level 2345 fenced off
# chkconfig --level 2345 cman off
# chkconfig --level 2345 ccsd off
4. Edit the cluster configuration file as follows:
Upgrading A Red Hat Clust er from RHEL 4 t o RHEL 5 a. At a cluster node, open /etc/cluster/cluster.conf with a text editor.
b. If your cluster is configured with GULM as the cluster manager, remove the GULM XML elements — <gulm> and </gulm> — and their content from
/etc/cluster/cluster.conf. GULM is not supported in Red Hat Cluster Suite for
RHEL 5.
Example G.1, “ GULM XML Elements and Content” shows an example of GULM
XML elements and content.
c. At the <clusternode> element for each node in the configuration file, insert
nodeid="number" after name="name". Use a number value unique to that node.
Inserting it there follows the format convention of the <clusternode> element in a
RHEL 5 cluster configuration file.
Note
The nodeid parameter is required in Red Hat Cluster Suite for RHEL 5. The parameter is optional in Red Hat Cluster Suite for RHEL 4. If your configuration file already contains nodeid parameters, skip this step.
d. When you have completed editing /etc/cluster/cluster.conf, save the file and copy it to the other nodes in the cluster (for example, using the scp command).
5. If your cluster is a GULM cluster and uses Red Hat GFS, change the superblock of each GFS file system to use the DLM locking protocol. Use the gfs_tool command with the sb and
proto options, specifying lock_dlm for the DLM locking protocol: gfs_tool sb device proto lock_dlm
For example:
# gfs_tool sb /dev/my_vg/gfs1 proto lock_dlm
You shouldn't change any of these values if the filesystem is mounted.
Are you sure? [y/n] y current lock protocol name = "lock_gulm" new lock protocol name = "lock_dlm"
Done
6. Update the software in the cluster nodes to RHEL 5 and Red Hat Cluster Suite for RHEL 5. You can acquire and update software through Red Hat Network channels for RHEL 5 and Red Hat
Cluster Suite for RHEL 5.
7. Run lvmconf --enable-cluster.
8. Enable cluster software to start upon reboot. At each node run /sbin/chkconfig as follows:
# chkconfig --level 2345 rgmanager on
# chkconfig --level 2345 gfs on
# chkconfig --level 2345 clvmd on
# chkconfig --level 2345 cman on
9. Reboot the nodes. The RHEL 5 cluster software should start while the nodes reboot. Upon verification that the Red Hat cluster is running, the upgrade is complete.
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Red Hat Ent erprise Linux 5 Clust er Administ rat ion
Examp le G .1. G ULM XML Elemen t s an d Co n t en t
<gulm>
<lockserver name="gulmserver1"/>
<lockserver name="gulmserver2"/>
<lockserver name="gulmserver3"/>
</gulm>
128
Revision History
Revisio n 10.0- 8
Version for 5.11 GA release
Mo n Sep 8 2014
Revisio n 10.0- 5 Mo n Ju n 30 2014
Beta release of Red Hat Enterprise Linux 5.11
St even Levin e
St even Levin e
Revisio n 10.0- 3 T u e Ju n 10 2014 St even Levin e
Resolves: #571695
Notes that Red Hat Enterprise Linux 5 supports bonding mode 1 only.
Resolves: #480291
Improves document index
Resolves: #1092636
Adds description of Startup Wait parameter to description of PostgreSQL 8 fields.
Revisio n 10.0- 2 Wed Ap r 30 2014
Latest draft for RHEL 5.11 release
St even Levin e
Revisio n 9 .0- 6 Mo n Sep 30 2013
Version for Red Hat Enterprise Linux 5.10 GA release
Revisio n 9 .0- 5 Wed Ju l 10 2013
Beta release of Red Hat Enterprise Linux 5.10
St even Levin e
St even Levin e
Revisio n 9 .0- 4 T u e May 28 2013 St even Levin e
Resolves: #960841
Documents need to set SELinux booleans for fence_xvm fencing agent operation.
St even Levin e Revisio n 9 .0- 3 T u e May 21 2013
Incorporating review comment re: note about SELinux.
Revisio n 9 .0- 1 Mo n May 20 2013
Clarifies usage of SELinux with virtual machines.
Revisio n 8.0- 6 Fri Jan 4 2013
Version for Red Hat Enterprise Linux 5.9 GA release
Revisio n 8.0- 5
Fixing typographical error
Wed Sep 26 2012
St even Levin e
St even Levin e
St even Levin e
Revisio n 8.0- 3 Wed Au g 29 2012
Beta release of Red Hat Enterprise Linux 5.9
St even Levin e
Resolves: #823649
Documents new attribute for file system resource agents to set NFS workarounds.
Revisio n 8.0- 1 T u e Ju l 31 2012 St even Levin e
Revision Hist ory
129
Red Hat Ent erprise Linux 5 Clust er Administ rat ion
Resolves: #742312
Documents support for IBM iPDU Fence Device
Resolves: #757902
Documents backup and restore of luci configuration using luci_admin command.
Resolves: #838154
Documents virtual machine resource configuration.
Resolves: #831343
Updates descriptions of luci fields and screens.
Resolves: #838131
Documents SSL attribute for HP iLO fence device.
Resolves: #712379
Adds an appendix on configuring high availability LVM.
Revisio n 7.0- 3 T h u Feb 16 2012
Release for GA of Red Hat Enterprise Linux 5.8
Resolves: #712376
Adds information on disabling cluster software.
Resolves: #712387
Adds information on stopping single resources of a cluster.
Resolves: #712593
Adds appendix on consensus timeout.
Resolves: #626495
Adds note on single site cluster support.
Revisio n 7.0- 2 T h u Dec 15 2011
Beta release of Red Hat Enterprise Linux 5.8
Revisio n 7.0- 1 T h u No v 10 2011
St even Levin e
St even Levin e
St even Levin e
130
Resolves: #571557
Adds note on managing virtual machines in a cluster.
Resolves: #742310
Documents new privilege level parameter for IPMI fence device.
Resolves: #747456
Corrects small typographical errors throughout document.
Resolves: #748935
Clarifies description of iptables firewall filters.
Resolves: #718084
Provides link to Support Essentials article.
Resolves: #749858
Documents support for RHEV-M REST API fence agent.
Resolves: #569585
Clarifies support statement for running Samba in a cluster.
Revisio n 6 .0- 1 T h u Ju l 21 2011 St even Levin e
Revision Hist ory
131
Red Hat Ent erprise Linux 5 Clust er Administ rat ion
Resolves: #713256
Documents new fence_vmware_soap agent.
Resolves: #446137
Documents procedure to configure a system to listen to luci from the internal network only.
Resolves: #515858
Provides information about cluster service status check and failover timeout.
Resolves: #560558
Provides rules to allow multicast traffic for cluster comunication
Resolves: #705131
Updates tables of fence agent parameters to reflect Red Hat Enterprise Linux 5.7 support.
Resolves: #705134
Documents non-critical resources and restart-disable configuration parameter.
Resolves: #480292
Adds pointer to cluster.conf schema in documentation of resource parameters.
Resolves: #515860
Updates example domains.
Resolves: #595711
Fixes minor typographical errors.
Resolves: #654176
Fixes minor typographical errors.
Resolves: #675809
Fixes incorrect table title reference.
Revisio n 5.0- 1 T h u Dec 23 2010 St even Levin e
Resolves: #664055
Adds newly-supported fence agents to Fence Device Parameters appendix.
Revisio n 4 .0- 1
Resolves: #511150
Clarifies support for SELinux.
Mo n Mar 15 2010
Resolves: #527473
Adds information about cluster node-count limit.
Resolves: #568179
Adds information about support of and GFS/GFS2 deployment.
Pau l Ken n ed y
Resolves: #568483
Adds general support statement.
Resolves: #526540
Clarifies meaning of Name parameter for fencing devices.
132
Index
Revisio n 3.0- 1 T u e Au g 18 2009
Resolves: #516128
Adds notes about not supporting IPV6.
Resolves: #482936
Corrects Section 5.7 title and intro text.
Resolves: #488751
Corrects iptables rules. Removed examples.
Pau l Ken n ed y
Resolves: #502053
Corrects iptables rules for rgmanager.
Resolves: #511150
Adds content stating that SELinux must be disabled for Red Hat Cluster Suite.
Resolves: #513072
Adds information about limitations on using SCSI reservations as a fencing method.
Revisio n 2.0- 1 T u e Jan 20 2009
Resolves: #458882
Explains Firewall settings for multicast address.
Pau l Ken n ed y
Resolves: #450777
Includes content about configuring failover domains to not fail back a service (an added feature).
Revisio n 1.0- 1 Wed May 21 2008 Mich ael Hid eo Smit h
Resolves: #232215
Changing from XML to HTML Single with floating Table of Contents and viewable by browser
Index
A
ACPI
- configuring,
Configuring ACPI For Use with Integrated Fence Devices
Ap ach e HT T P Server
-
httpd.conf , Installing and Configuring the Apache HTTP Server
-
setting up service, Example of Setting Up Apache HTTP Server
Ap ach e server reso u rce ag en t , HA Reso u rce Paramet ers
APC p o wer swit ch ,
APC p o wer swit ch o ver SNMP, Fen ce Device Paramet ers
B
b eh avio r, HA reso u rces, HA Reso u rce Beh avio r
Bro cad e f ab ric swit ch ,
Bu ll PAP ( Plat f o rm Ad min ist rat io n Pro cesso r) ,
C
133
Red Hat Ent erprise Linux 5 Clust er Administ rat ion
Cisco MDS,
Cisco UCS, Fen ce Device Paramet ers
clu st er
administration, Before Configuring a Red Hat Cluster
With Conga , Managing Red Hat Cluster With system-config-cluster
- diagnosing and correcting problems, Diagnosing and Correcting Problems in a
Cluster , Diagnosing and Correcting Problems in a Cluster
- disabling the cluster software,
Disabling the Cluster Software
- displaying status,
, Managing High-Availability Services
- managing node,
-
starting, Starting the Cluster Software
-
starting, stopping, restarting, and deleting, Starting, Stopping, and Deleting Clusters
clu st er ad min ist rat io n , Bef o re Co n f ig u rin g a Red Hat Clu st er
Clu st er Wit h Co n g a , Man ag in g Red Hat Clu st er Wit h syst em- co n f ig - clu st er
- backing up the cluster database,
Backing Up and Restoring the Cluster Database
- compatible hardware,
-
configuring ACPI, Configuring ACPI For Use with Integrated Fence Devices
-
configuring iptables, Enabling IP Ports
-
configuring max_luns, Configuring max_luns
- Conga considerations,
Considerations for Using Conga
- considerations for using qdisk,
Considerations for Using Quorum Disk
-
considerations for using quorum disk, Considerations for Using Quorum Disk
- diagnosing and correcting problems in a cluster, Diagnosing and Correcting
Problems in a Cluster , Diagnosing and Correcting Problems in a Cluster
- disabling the cluster software,
Disabling the Cluster Software
- displaying cluster and service status,
- enabling IP ports,
- general considerations,
General Configuration Considerations
- managing cluster node,
-
managing high-availability services, Managing High-Availability Services
-
modifying the cluster configuration, Modifying the Cluster Configuration
-
network switches and multicast addresses, Multicast Addresses
- restoring the cluster database,
Backing Up and Restoring the Cluster Database
-
SELinux, Red Hat Cluster Suite and SELinux
- starting and stopping the cluster software, Starting and Stopping the Cluster
- starting, stopping, restarting, and deleting a cluster, Starting, Stopping, and Deleting
-
virtual machines, Configuring Virtual Machines in a Clustered Environment
clu st er co n f ig u rat io n ,
Co n f ig u rin g Red Hat Clu st er Wit h Co n g a
- modifying,
Modifying the Cluster Configuration
Clu st er Co n f ig u rat io n T o o l
- accessing,
clu st er d at ab ase
-
backing up, Backing Up and Restoring the Cluster Database
- restoring,
Backing Up and Restoring the Cluster Database
134
Index
D
Dell DRAC, Fen ce Device Paramet ers
E
clu st er reso u rce st at u s ch eck, Clu st er Service Reso u rce Ch eck an d Failo ver
clu st er reso u rce t yp es, Co n sid erat io n s f o r Co n f ig u rin g HA Services
clu st er service
- displaying status,
, Managing High-Availability Services
clu st er service man ag ers
configuration, Adding a Cluster Service to the Cluster
, Adding a Cluster Service to the Cluster , Propagating The Configuration File: New Cluster
clu st er services, Ad d in g a Clu st er Service t o t h e Clu st er
, Ad d in g a Clu st er Service t o t h e Clu st er
- (see also adding to the cluster configuration)
- Apache HTTP Server, setting up,
Example of Setting Up Apache HTTP Server
-
httpd.conf , Installing and Configuring the Apache HTTP Server
clu st er so f t ware
-
configuration, Configuring Red Hat Cluster With Conga
- disabling,
Disabling the Cluster Software
- installation and configuration, Configuring Red Hat Cluster With system-configcluster
-
starting and stopping, Starting and Stopping the Cluster Software
clu st er st o rag e
-
configuration, Configuring Cluster Storage
co mman d lin e t o o ls t ab le,
Co mman d Lin e Ad min ist rat io n T o o ls
co n f ig u rat io n
-
HA service, Considerations for Configuring HA Services
co n f ig u rat io n f ile
- propagation of,
Propagating The Configuration File: New Cluster
co n f ig u rin g clu st er st o rag e ,
Co n f ig u rin g Clu st er St o rag e
Co n f ig u rin g Hig h Availab ilit y LVM, Hig h Availab ilt y LVM ( HA- LVM)
Co n g a
- accessing,
Configuring Red Hat Cluster Software
- considerations for cluster administration,
Considerations for Using Conga
-
Eg en era SAN co n t ro ller,
F
f ailo ver t imeo u t , Clu st er Service Reso u rce Ch eck an d Failo ver T imeo u t
135
Red Hat Ent erprise Linux 5 Clust er Administ rat ion f eed b ack,
f en ce d evice
-
APC power switch, Fence Device Parameters
-
APC power switch over SNMP, Fence Device Parameters
-
Brocade fabric switch, Fence Device Parameters
- Bull PAP (Platform Administration Processor),
- Cisco MDS,
- Cisco UCS,
-
Dell DRAC, Fence Device Parameters
-
Egenera SAN controller, Fence Device Parameters
-
Fujitsu Siemens Remoteview Service Board (RSB), Fence Device Parameters
-
GNBD (Global Network Block Device), Fence Device Parameters
-
HP iLO (Integrated Lights Out), Fence Device Parameters
-
HP iLO (Integrated Lights Out) MP, Fence Device Parameters
- IBM Blade Center,
-
IBM iPDU, Fence Device Parameters
-
IBM Remote Supervisor Adapter II (RSA II), Fence Device Parameters
-
IF MIB, Fence Device Parameters
- IPMI (Intelligent Platform Management Interface) LAN,
- manual fencing,
-
McData SAN switch, Fence Device Parameters
-
QLogic SANBox2 switch, Fence Device Parameters
- RHEV-M REST API,
-
RPS-10 power switch, Fence Device Parameters
-
SCSI fencing, Fence Device Parameters
-
virtual machine fencing, Fence Device Parameters
-
Vixel SAN switch, Fence Device Parameters
- VMware (SOAP interface),
- WTI power switch,
Fence Device Parameters f ilesyst em reso u rce ag en t , HA Reso u rce Paramet ers
Fu jit su Siemen s Remo t eview Service Bo ard ( RSB) , Fen ce Device Paramet ers
G g en eral
- considerations for cluster administration,
General Configuration Considerations
G FS f ile syst em reso u rce ag en t ,
G NBD ( G lo b al Net wo rk Blo ck Device) , Fen ce Device Paramet ers
H
HA service co n f ig u rat io n
-
overview, Considerations for Configuring HA Services
h ard ware
-
compatible, Compatible Hardware
HP iLO ( In t eg rat ed Lig h t s O u t ) , Fen ce Device Paramet ers
HP iLO ( In t eg rat ed Lig h t s O u t ) MP, Fen ce Device Paramet ers
HT T P services
- Apache HTTP Server
-
httpd.conf, Installing and Configuring the Apache HTTP Server
- setting up,
Example of Setting Up Apache HTTP Server
136
Index
I
L
LVM reso u rce ag en t ,
LVM, Hig h Availab ilit y, Hig h Availab ilt y LVM ( HA- LVM)
M man u al f en cin g ,
max_lu n s
- configuring,
McDat a SAN swit ch , Fen ce Device Paramet ers
mu lt icast ad d resses
- considerations for using with network switches and multicast addresses, Multicast
MySQ L reso u rce ag en t , HA Reso u rce Paramet ers
N
IBM Blad e Cen t er, Fen ce Device Paramet ers
IBM iPDU,
IBM Remo t e Su p erviso r Ad ap t er II ( RSA II) , Fen ce Device Paramet ers
IF MIB, Fen ce Device Paramet ers
in t eg rat ed f en ce d evices
-
configuring ACPI, Configuring ACPI For Use with Integrated Fence Devices
in t ro d u ct io n ,
-
other Red Hat Enterprise Linux documents, Introduction
IP ad d ress reso u rce ag en t , HA Reso u rce Paramet ers
IP p o rt s
- enabling,
IPMI ( In t ellig en t Plat f o rm Man ag emen t In t erf ace) LAN, Fen ce Device Paramet ers
ip t ab les
- configuring,
NFS clien t reso u rce ag en t , HA Reso u rce Paramet ers
NFS exp o rt reso u rce ag en t , HA Reso u rce Paramet ers
NFS mo u n t reso u rce ag en t , HA Reso u rce Paramet ers
O
o p en LDAP reso u rce ag en t , HA Reso u rce Paramet ers
O racle 10g f ailo ver in st an ce reso u rce ag en t ,
O racle DB reso u rce ag en t ,
137
Red Hat Ent erprise Linux 5 Clust er Administ rat ion
O racle list en er reso u rce ag en t ,
P
Q q d isk
- considerations for using,
Considerations for Using Quorum Disk
Q Lo g ic SANBo x2 swit ch , Fen ce Device Paramet ers
q u o ru m d isk
- considerations for using,
Considerations for Using Quorum Disk
R p aramet ers, f en ce d evice,
p aramet ers, HA reso u rces,
Po st g resSQ L 8 reso u rce ag en t ,
relat io n sh ip s
- cluster resource,
Parent, Child, and Sibling Relationships Among Resources
reso u rce ag en t
- Apache server,
-
filesystem, HA Resource Parameters
-
GFS file system, HA Resource Parameters
- IP address,
- LVM,
- MySQL,
- NFS client,
- NFS export,
- NFS mount,
-
open LDAP, HA Resource Parameters
-
Oracle 10g failover instance, HA Resource Parameters
-
Oracle DB, HA Resource Parameters
-
Oracle listener, HA Resource Parameters
-
PostgresSQL 8, HA Resource Parameters
-
Samba service, HA Resource Parameters
-
SAP database, HA Resource Parameters
-
SAP instance, HA Resource Parameters
-
Sybase ASE failover instance, HA Resource Parameters
-
Tomcat 5, HA Resource Parameters
RHEV- M REST API, Fen ce Device Paramet ers
RPS- 10 p o wer swit ch , Fen ce Device Paramet ers
S
Samb a service reso u rce ag en t ,
SAP d at ab ase reso u rce ag en t ,
SAP in st an ce reso u rce ag en t , HA Reso u rce Paramet ers
SCSI f en cin g , Fen ce Device Paramet ers
SELin u x
- configuring,
Red Hat Cluster Suite and SELinux
138
Index st art in g t h e clu st er so f t ware,
St art in g t h e Clu st er So f t ware
st at u s ch eck, clu st er reso u rce, Clu st er Service Reso u rce Ch eck an d Failo ver
Syb ase ASE f ailo ver in st an ce reso u rce ag en t , HA Reso u rce Paramet ers
Syst em V in it , St art in g an d St o p p in g t h e Clu st er So f t ware
T t ab le
-
command line tools, Command Line Administration Tools
t ab les
-
T o mcat 5 reso u rce ag en t , HA Reso u rce Paramet ers
t ro u b lesh o o t in g
- diagnosing and correcting problems in a cluster, Diagnosing and Correcting
Problems in a Cluster , Diagnosing and Correcting Problems in a Cluster
t yp es
- cluster resource,
Considerations for Configuring HA Services
U
u p g rad in g , RHEL 4 t o RHEL 5, Up g rad in g A Red Hat Clu st er f ro m RHEL 4 t o RHEL 5
V
virt u al mach in es, in a clu st er, Co n f ig u rin g Virt u al Mach in es in a Clu st ered
Vixel SAN swit ch ,
VMware ( SO AP in t erf ace) , Fen ce Device Paramet ers
W
WT I p o wer swit ch , Fen ce Device Paramet ers
139
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