1. Introduction. Symantec NetBackup 7.5

Chapter

1

Introduction

This chapter includes the following topics:

■

Snapshot Client features at a glance

■

What’s new in NetBackup Snapshot Client 7.5

■

Important information about Replication Director

■

Snapshot Client features

■

About snapshot basics

■

Benefits of copy-on-write vs mirror

■

About local backup of a snapshot

■

Off-host backup overview

■

Off-host backup methods

■

Snapshot Client requirements

■

Snapshot Client terminology

■

Snapshot Client assistance

■

About open file backups for Windows

Snapshot Client features at a glance

NetBackup Snapshot Client provides a variety of snapshot-based features for

NetBackup. It supports clients on UNIX, Linux, and Windows platforms, on Fibre

Channel networks (SANs) or traditional LANs.

18 Introduction

Snapshot Client features at a glance

Table 1-1 Snapshot Client features at a glance

Snapshot Client feature

Snapshot

Description

A point-in-time, read-only, disk-based copy of a client volume. NetBackup backs up data from the snapshot, not directly from the client’s primary or original volume.

Required by all features of Snapshot Client.

Instant Recovery

Off-host backup

Makes the backups available for recovery from disk.

Shifts the burden of backup processing onto a separate backup agent, reducing the backup impact on the client’s computing resources. The backup agent sends the client’s data to the storage device.

Includes alternate the client, data mover, and virtual machine host (for VMware).

Note: NetBackup 7.1 supports off-host backup of Oracle database in the SFRAC (Storage Foundation Real

Application Clusters) environment. For more details, refer to the Symantec NetBackup for Oracle System

Administrator’s Guide.

FlashBackup

NetBackup for Hyper-V

NetBackup for VMware

Combines the speed of raw-partition backups with the ability to restore individual files.

Backs up and restores Windows and Linux Hyper-V virtual machines (guest operating systems).

See the NetBackup for Hyper-V Administrator's Guide.

Backs up and restores Windows and Linux VMware virtual machines (guest operating systems).

See the NetBackup for VMware Administrator's Guide.

RealTime

NAS snapshot

Allows restore of data from any point in time.

Makes snapshot-based backups of data on a Network

Attached Storage (NAS) host.

Block level incremental backup

(BLIB)

Enables NetBackup to back up only the changed data blocks of VMware virtual machines and Oracle or DB2 database files.

Introduction

What’s new in NetBackup Snapshot Client 7.5

19

Table 1-1 Snapshot Client features at a glance (continued)

Snapshot Client feature Description

NetBackup Replication Director The implementation of NetBackup

OpenStorage-managed snapshot replication, where the snapshots are stored on the storage systems of partnering companies. Replication is conducted per defined operations in storage lifecycle policies.

See the NetBackup Replication Director Solutions Guide.

What’s new in NetBackup Snapshot Client 7.5

Replication Director is the new feature for Snapshot Client 7.5. Replication Director is the implementation of NetBackup OpenStorage-managed snapshot replication, where the snapshots are stored on the storage systems of vendors. Storage replication technology provides an efficient means to send copies of user data

(files, applications, databases) to off-site storage as part of a disaster recovery plan. In this release, snapshot replication is supported only between NetApp filers.

Refer to the Symantec NetBackup™ Replication Director Solutions Guide for detailed information about Replication Director.

Replication Director offers a single NetBackup interface for end-to-end data protection management for the tasks that include the following:

■ Unified policy management.

Use one, centralized backup infrastructure to manage the lifecycle of all data.

Multiple data centers can replicate to one disaster recovery domain or one data center. Inter-domain replication however, is not supported in this release.

Additional media servers are not needed in the remote data centers.

■ Snapshot copy management.

Use NetBackup to create the initial snapshot, to configure the total number of copies to be created, and to configure the retention period for each copy.

■ Snapshot copy monitoring.

Use NetBackup OpsCenter to monitor the creation of each copy at each storage location. OpsCenter provides extensive reporting on the entire replication environment.

■ Global search and restore.

Recovery is available from any storage device in the environment that is defined to NetBackup. The recovery is from the primary copy or any replicated copy on disk, or from any duplicated copy on disk or tape.

20 Introduction

Important information about Replication Director

Note: Only rollback restore from copy one is supported in the 7.5 release.

Replication Director makes use of OpenStorage, a Symantec API that allows

NetBackup to communicate with the storage implementations that conform to the API.

Replication Director uses the capabilities of NetApp to perform the following functions:

■ Share disks.

Multiple heterogeneous media servers can access the same disk volume concurrently.

■ Balance loads and tune performance.

NetBackup balances backup jobs and storage usage among the media servers and disk pools.

■ Make full use of disk appliance capabilities, including fast storage provisioning and almost unlimited storage.

■ An alternative to off-site vaulting.

NetBackup 7.5 introduces two new policies for the VMware and Hyper-V virtual machines. The policy types are VMware and Hyper-V. Use these policy types to configure the Snapshot Client policies.

For more information, see the NetBackup Replication Director Solutions Guide.

Important information about Replication Director

Listed is important information related to the Replication Director feature:

■ NetApp offers an import tool to migrate DataFabric Manager server datasets and Data ONTAP relationships into NetBackup. Once in NetBackup, the snapshot data can be managed using Replication Director.

■ When you create a policy, note that the OST_FIM method works only if the

Policy storage attribute points to a storage lifecycle policy that contains a snapshot-capable storage unit.

■ The OST_FIM method provides two configuration parameters. The Snapshot

Type and the Maximum Snapshots parameters.

The Snapshot Type parameter indicates which snapshot technology is to be used by the OpenStorage partner to create the snapshot. The snapshot technologies are 0-Auto, 1-Clone, 2-Plex, and 3-Diff.

Table 1-2

Introduction

Important information about Replication Director

21

The Maximum Snapshots parameter sets the maximum number of Instant

Recovery snapshots to be retained at one time. When the maximum is reached, the next snapshot causes the oldest to be deleted. The parameter is applicable for Instant Recovery only.

Table 1-2 lists the snapshot technology information

Snapshot technology

0-Auto

Description

1-Clone

2-Plex

3-Diff

This parameter indicates to the partner to use the best snapshot technology available to that particular partner to create the snapshot.

For example, when 0 is indicated, the OpenStorage partner NetApp selects 3-Diff.

This parameter indicates to the partner to create an independent copy of the volume. The copy process can take some time as the entire copy must be complete.

The snapshot that is created is independent of the source.

This parameter indicates to the partner to create a snapshot that is completely independent of the source snapshot. This parameter is based on mirror-break-off technology.

When a mirror device is attached to the source, the contents of the mirror device are exactly the same as that of the source device.

When the relationship is broken between the two, the mirror device is separated from the source. The mirror device acts as a point-in-time copy.

This parameter indicates to the partner to create a snapshot that is completely dependent on the source. This parameter is based on copy-on-write technology.

The device creates a cache object to maintain the original blocks of the snapshot when the blocks are modified.

■ Do not use the Policy Configuration Wizard or the Getting Started Wizard to configure a snapshot policy for Replication Director.

Importing the existing NetApp relationship into the control of

NetBackup

NetApp offers an import tool to migrate DataFabric Manager server datasets and

DataONTAPrelationships into NetBackup. Once in NetBackup, the snapshot data can be managed using Replication Director.

22 Introduction

Snapshot Client features

The NetApp import tool allows the administrator to perform the following actions:

■ Export the dataset configuration from the DataFabric Manager server into an

XML file.

■ Edit the XML file to change the backup policies or topology.

■ Import the XML file into NetBackup.

For more information on the import tool, see the NetApp Plug-in 1.0 for Symantec

NetBackup Replication Director Installation and Administration Guide, available from the NetApp Support Site .

Snapshot Client features

These topics describe the features of Snapshot Client.

About snapshots

A snapshot is a point-in-time, read-only, disk-based copy of a client volume. After the snapshot is created, NetBackup backs up data from the snapshot, not directly from the client’s primary or original volume. Users and client operations can access the primary data without interruption while data on the snapshot volume is being backed up. The contents of the snapshot volume are cataloged as if the backup was produced directly from the primary volume. After the backup is complete, the snapshot-based backup image on storage media is indistinguishable from a backup image produced by a traditional, non-snapshot backup.

All the features of Snapshot Client (including off-host backup, FlashBackup, and

Instant Recovery) require the creation of a snapshot.

About snapshot methods

NetBackup can create different types of snapshots. Each snapshot type that you configure in NetBackup is called a snapshot method. Snapshot methods enable

NetBackup to create snapshots within the storage stack (such as the file system, volume manager, or disk array) where the data resides. If the data resides in a logical volume, NetBackup can use a volume snapshot method to create the snapshot. If the data resides in a file system, NetBackup can use a file system method, depending on the client OS and the file system type.

Just as many different technologies are available for creating snapshots, many different terms are used to refer to the underlying implementation of any given snapshot. Common terms include clone, split-mirror, and copy-on-write. In this documentation, the term "snapshot" designates any point-in-time, read-only copy of a primary volume, regardless of its underlying implementation. Method-specific

Introduction

Snapshot Client features

23 terminology is explained along with specific snapshot methods in other chapters of this guide.

In some cases, more than one method could make the snapshot. If the data resides in a file system over a logical volume, NetBackup could use a file system method or logical volume method. The choice of method might depend on the snapshot features available in the storage subsystem where the data resides. Or, the choice might depend on the requirements of the snapshot method itself. For example: if the client data is in a VxFS file system over a VxVM volume, NetBackup could create the snapshot with a file system method. On the other hand, NetBackup could use a volume manager method to create the snapshot of the same data, such as VxVM or FlashSnap. Between VxVM and FlashSnap, only FlashSnap supports the Persistent FastResync feature of VxVM mirror volumes. To take advantage of the Persistent FastResync feature, you would have to select the FlashSnap method.

About snapshot providers

Each snapshot method relies on the snapshot technology that is built into the storage subsystem where the data is stored. Examples of storage subsystem are volume manager, file system, or hardware disk array. NetBackup includes a set of software libraries that are called "snapshot providers." The providers enable

Snapshot Client to access the snapshot technology in the storage subsystem.

Each snapshot provider is designed for a particular subsystem. For example, the

VxFS provider enables NetBackup to create snapshots of files in the Veritas File

System (VxFS). The VxVM provider does the same for data that is configured in

Veritas Volume Manager volumes. The EMC CLARiiON disk array provider enables

NetBackup to create hardware snapshots in the CLARiiON array.

You specify the method in the NetBackup policy. When the policy runs, the snapshot method calls the snapshot provider library. The provider then accesses the underlying commands in the storage subsystem to create the snapshot.

24 Introduction

Snapshot Client features

Figure 1-1 Simplified view of NetBackup access to snapshot technology

Snapshot method selected in NetBackup policy

Snapshot provider library

Storage subsystem (file system, volume, raw device, disk array)

About off-host backup support

Another major component of NetBackup Snapshot Client is support for off-host backup. Off-host backup shifts the burden of backup processing onto a separate backup agent, greatly reducing the backup impact on the client’s computing resources. The backup agent sends the client’s data to the storage device.

Figure 1-2

shows a backup agent.

Figure 1-2 Backup agent for off-host backup

NetBackup master server

LAN / WAN

NetBackup client

Backup agent

SCSI

Local client data storage

Disks of client data on SAN

Fibre Channel/SAN

Backup agent

Robot on

SAN

Introduction

Snapshot Client features

25

The backup agent can be any of the following:

■ an additional (alternate) client

■ a NetBackup media server or a third-party copy device that implements the

SCSI Extended Copy command

■ a NAS host (Network Attached Storage)

Note that many types of devices are designed to act as third-party copy devices, such as routers, bridges, robotic libraries, and disk arrays. The backup agent can direct the data to SCSI-attached storage or to storage on the SAN.

Note: NetBackup 7.1 supports off-host backup of Oracle database in the SFRAC

(Storage Foundation Real Application Clusters) environment. For more details, refer to the Symantec NetBackup for Oracle System Administrator’s Guide.

About Instant Recovery

This feature makes backups available for quick recovery from disk. Instant

Recovery combines snapshot technology—the image is created with minimal interruption of user access to data—with the ability to do rapid snapshot-based restores. The snapshot is retained on disk as a full backup image. The snapshot can also be the source for an additional backup copy to tape or other storage.

Instant Recovery makes possible three additional variations of restore: block-level restore, file promotion, and snapshot rollback.

See

“Instant Recovery restore features”

on page 266.

About FlashBackup policies

FlashBackup is a policy type that combines the speed of raw-partition backups with the ability to restore individual files.

About snapshot methods for disk arrays

Snapshot Client supports snapshot methods for many disk arrays. Each array method is designed for a particular disk array series and a particular snapshot type.

These methods support the following:

■ Mirror, clone, and copy-on-write snapshot types.

■ NetBackup Instant Recovery, both snapshot-only and snapshot-to-tape backup.

■ Local backup or alternate client backup.

26 Introduction

About snapshot basics

■ Backup of Oracle, Exchange, and DB2 database clients.

About block level incremental backup

Block level incremental backup enables NetBackup to back up only the changed data blocks of VMware virtual machines and Oracle or DB2 database files. For details, refer to the appropriate NetBackup database agent guide or to the

NetBackup for VMware Administrator's Guide.

About Snapshot Client and NDMP

Using the NDMP protocol version V4 snapshot extension, NetBackup Snapshot

Client can make policy-based snapshots of data on a Network Attached Storage

(NAS) host. The snapshot is stored on the same NAS device that contains the primary client data. From the snapshot, you can restore individual files or roll back an entire volume or file system, by means of Instant Recovery.

Note: NetBackup for NDMP add-on software is required, and the NAS vendor must support snapshots.

About snapshot basics

Large active databases or file systems that must be available around-the-clock are difficult to back up without incurring a penalty. Often, the penalty takes one of the following forms:

■ To allow time for the backup, the entire database is taken offline or the file system is unmounted. The result is suspension of service and inconvenience to users.

■ The copy is made very quickly but produces an incomplete version of the data, since some transactions have failed to complete.

A solution to this problem is to create a snapshot of the data. A snapshot captures the data at a particular instant, without causing client downtime. The resulting capture or snapshot can be backed up without affecting the performance or availability of the file system or database. Without a complete, up-to-date snapshot of the data, a correct backup cannot be made.

When a NetBackup media server or third-party copy device manages the backup, the data to back up must be contained in a snapshot. The backup agent can only access the data by means of the raw physical disk. Once the data is captured as a snapshot, the NetBackup client "maps" the logical representation of the data to

Introduction

About snapshot basics

27 its physical disk address. These disk addresses are sent to the backup agent over the LAN. The data is then read from the appropriate disk by the backup agent.

See

“Off-host backup overview”

on page 30.

Two types of snapshots are available, both supported by NetBackup: copy-on-write and mirror (or clone).

About the copy-on-write snapshot type

A copy-on-write type of snapshot is a detailed account of data as it existed at a certain moment. A copy-on-write snapshot is not a copy of the data, but a specialized account of it.

A copy-on-write snapshot is created in the client’s file system or in a raw partition.

The copy-on-write is not created as a complete copy of the client data on a separate or mirror disk. The snapshot is then backed up to storage as specified in the backup policy. Users can access their data without interruption, as though no backup is underway. The file system is paused long enough to assemble a transactionally consistent record.

See

“How copy-on-write works”

on page 312.

Note that VxFS allows two kinds of copy-on-write snapshots: file system snapshots and Storage Checkpoints.

See

“Benefits of copy-on-write vs mirror”

on page 28.

About the mirror snapshot type

Unlike a copy-on-write, a mirror is a complete data copy stored on a separate disk, physically independent of the original. Every change or write to the data on the primary disk is also made to the copy on the secondary disk. The copy is a "mirror" image of the source data.

28 Introduction

Benefits of copy-on-write vs mirror

Figure 1-3

NetBackup client

Source is copied to mirror

All data that is written to source is also written to mirror

Source image (on primary disk)

Mirror image (on secondary)

As in a copy-on-write, transactions are allowed to finish and new I/O on the primary disk is briefly halted. When the mirror image is brought up-to-date with the source, the mirror is split from the primary. After the mirror is split, new changes can be made to the primary but not to the mirror. The mirror can now be backed up (see next diagram).

Mirror is split from source Figure 1-4

NetBackup client

Mirror is split from source: further writes to source are not made to mirror.

Source image (on primary disk)

Mirror image (on secondary)

If the mirror is to be used again it must be brought up-to-date with the primary volume (synchronized). During synchronization, the changes that were made to the primary volume—while the mirror was split—are written to the mirror.

Since mirroring requires a complete copy of the primary on a separate device

(same size as the primary), it consumes more disk space than copy-on-write.

See

“Benefits of copy-on-write vs mirror”

on page 28.

Benefits of copy-on-write vs mirror

Table 1-3

compares the benefits of the two types of snapshots.

Introduction

About local backup of a snapshot

29

Table 1-3 Comparative benefits of copy-on-write and mirror

Benefits of copy-on-write Benefits of mirror

■

■

■

Consumes less disk space: no need for secondary disks containing complete copies of source data.

Relatively easy to configure (no need to set up mirror disks).

Creates a snapshot much faster than one created by a large, unsynchronized mirror, because mirror synchronization can be time consuming.

■

■

Has less impact on the performance of the host being backed up (NetBackup client), because the copy-on-write mechanism is not needed.

Allows for faster backups: the backup process reads data from a separate disk

(mirror) operating independently of the primary disk that holds the client’s source data. Unlike copy-on-write, disk

I/O is not shared with other processes or applications. Apart from NetBackup, no other applications have access to the mirror disk. During a copy-on-write, other applications as well as the copy-on-write mechanism can access the source data.

Note: If additional disk drives are available and volumes have been configured with the

Veritas Volume Manager, a mirror snapshot method is usually a good choice.

About local backup of a snapshot

A snapshot can be backed up to any NetBackup storage device. A Fibre Channel network or SAN is not required. The following diagram shows a network configuration sufficient for backing up a snapshot on the primary client (sometimes referred to as a "local" snapshot backup). The network configuration is identical to the configuration for normal NetBackup (no snapshot).

30 Introduction

Off-host backup overview

Figure 1-5 Snapshot backup on local network (no Fibre Channel/SAN required)

NetBackup master server

LAN / WAN

SCSI

SCSI

NetBackup client

Client’s disks storage

NetBackup media server

The figure shows the following phases in the local backup process:

Phase

Phase 1

Phase 2

Phase 3

Phase 4

Action

NetBackup master server tells the client to create the snapshot of the primary data.

Client reads the snapshot, formats a backup image reflecting the primary data, and writes the image to the media server.

Media server reads the backup image.

Media server writes data to local storage.

Off-host backup overview

One of the principal goals of NetBackup Snapshot Client is to move I/O processing off the primary NetBackup client to a backup agent.

Table 1-4

describes the types of backup agents.

Table 1-4 Type of backup agents

Type of backup agent

Alternate client

Description

A secondary or an alternate client performs the backup on behalf of the primary client. Compared to the other off-host methods, this approach reduces the backup I/O burden on the primary client to the greatest extent.

Introduction

Off-host backup overview

31

Table 1-4 Type of backup agents (continued)

Type of backup agent

Data Mover: NetBackup Media

Server (UNIX clients only)

Description

A NetBackup media server reads raw data from the client snapshot and writes it to a storage device, using mapping information that the client provides.

Data Mover: Network Attached

Storage

An NDMP (NAS) host performs the snapshot-only backup for Instant Recovery only.

Data Mover: Third-Party Copy

Device Data Mover (UNIX clients only)

A third-party copy device reads raw data from the client snapshot and writes the data to a storage device. To do so, the third-party copy device uses the Extended Copy command and mapping information from the client.

Many kinds of devices, such as routers and disk arrays, are designed as third-party copy devices.

A list of supported third-party copy devices is available.

See

“Snapshot Client assistance”

on page 47.

Data Mover: NDMP

Virtual machine host

Use to replicate NDMP snapshots. Select this agent in a policy that uses NDMP with Replication Director.

For more information about configuring a policy to use

NDMP with Replication Director, see the NetBackup

Replication Director Solutions Guide.

A VMware backup host performs backups on behalf of the virtual machines. The host can also be configured as a NetBackup master or media server.

About file and volume mapping methods

The NetBackup Media Server and Third-Party Copy Device backup agents are unaware of logical organizations of data such as file systems and volume managers.

The agent can access the data only from the physical disk address location. In order for NetBackup to perform this type of backup, it must translate the logical representation of the data to its physical disk addresses. This logical-to-physical translation process is referred to as mapping the data. During the backup, the mapping information is transmitted to the media server.

The mapping methods are installed as part of the NetBackup Snapshot Client product. NetBackup automatically selects the correct mapping method, depending on whether the backup data is configured over physical devices, logical volumes, or file systems.

32 Introduction

Off-host backup methods

Off-host backup methods

NetBackup Snapshot Client supports several forms of off-host backup, as explained in the following sections.

About alternate client backup

With this feature, all backup processing is off-loaded to another client. Off-loading the work to an alternate client saves computing resources on the primary client.

The alternate client handles the backup I/O processing, and the backup has little or no impact on the primary client.

The following diagram shows alternate client backup. A NetBackup master server is connected by means of a local or wide-area network to two clients and a media server. The primary NetBackup client contains the data to be backed up. A snapshot of that data is created on the alternate client (perhaps at another site). The alternate client creates a backup image from the snapshot, using original path names, and streams the image to the media server.

Figure 1-6 Alternate client backup: backup is performed on alternate client

(Detail from policy attributes dialog.)

NetBackup master server

LAN / WAN primary client

Data sharing

(mirrors or replication) alternate client media server storage

The figure shows the following phases in the alternate client backup process:

Phase

Phase 1

Phase 2

Action

Primary and alternate client collaborate to create the snapshot on the alternate client.

Alternate client sends the snapshot data to the media server.

Introduction

Off-host backup methods

33

Phase

Phase 3

Phase 4

Action

Media server reads the snapshot data from the alternate client.

Media server writes data to local storage.

About data sharing between clients

For alternate client backup, the original (primary) and alternate client must collaborate to create a snapshot. The following sections highlight two configurations: hardware array split-mirror snapshot and volume manager snapshot with data replication. Other configurations are possible, depending on the hardware and the snapshot method.

Alternate client backup split mirror examples

The alternate client has access to mirror disks which contain a snapshot of the primary client’s data. Before the backup, the mirror is split from the primary disk, which creates the snapshot on the mirror disk. The alternate client has access to the mirror disk, from which it creates and streams a snapshot-based backup image to the media server. After the backup, the mirror can be optionally resynchronized with the primary disk.

Note: The mirror disk need not be visible to the primary client, only to the alternate client.

Figure 1-7 Alternate client and split mirror: primary client and alternate client share data through mirroring.

NetBackup master server

LAN / WAN primary client

(Detail from policy attributes dialog.) alternate client media server storage

Primary disk mirror disk

34 Introduction

Off-host backup methods

The figure shows the following phases:

Phase

Phase 1

Phase 2

Phase 3

Phase 4

Action

Mirror disk is synchronized with primary.

Primary client collaborates with the alternate client to create the snapshot, splitting the mirror disk from primary disk and mounting the snapshot on the alternate client.

Alternate client streams the snapshot-based backup from the mirror to the media server.

Media server reads the backup image from the alternate client.

Figure 1-8

shows the media server and alternate client on the same host.

Figure 1-8 Alternate client and media server on same host

(Detail from policy attributes dialog.)

NetBackup master server

LAN / WAN primary client alternate client/ media server

Primary disk mirror disk storage

The figure shows the following phases:

Phase

Phase 1

Action

Mirror disk is synchronized with primary.

LAN / WAN

Introduction

Off-host backup methods

35

Phase

Phase 2

Phase 3

Action

Primary client collaborates with the alternate client to create the snapshot, splitting the mirror disk from primary disk and mounting the snapshot on the alternate client.

Media server (serving as alternate client) reads the snapshot-based backup from the mirror.

A single alternate client can handle backups for a number of primary clients, as shown in the following diagram.

Multiple clients can share an alternate backup client of the same operating system type.

Note: All clients must be of the same OS.

Figure 1-9 Alternate client for multiple primary clients client client client alternate client/ media server storage

36 Introduction

Off-host backup methods

Figure 1-10 Multiple clients with SSO: alternate client performs backup for multiple primary clients with NetBackup SSO option on a SAN

LAN / WAN

Solaris clients

Solaris

Alternate client/ media server, with

SSO

Windows clients

Fibre Channel/SAN

Shared

Storage

Windows

Alternate client/ media server, with

SSO

Alternate client backup through data replication example (UNIX only)

A volume configured with a software mirror on the alternate client replicates a volume that is on the primary client. When the backup starts, the replication is suspended and the software mirror is split from the replicating volume to form a snapshot on the alternate client. The snapshot is mounted on the alternate client and is used to complete the backup. After the backup, the snapshot volume is unmounted. The mirror is resynchronized with the replicating volume, and the replication is resumed.

Introduction

Off-host backup methods

37

Figure 1-11 Replication: primary client and alternate client share data through replication

NetBackup master server

LAN / WAN primary client replication

(Detail from policy attributes dialog.

Requires the VVR snapshot method.) alternate client media server primary volume

The NetBackup client’s primary volume is replicated on an alternate client.

replicating volume mirror volume

Storage

Phase

Phase 1

Phase 2

Phase 3

Phase 4

Action

Primary client collaborates with the alternate client to create snapshot.

Alternate client creates the snapshot by splitting mirror from replicating volume.

Alternate client sends the snapshot data from the snapshot to the media server.

Media server reads the snapshot data from the alternate client.

Media server writes data to storage.

Phase 5

Only the VVR snapshot method for UNIX clients supports this configuration. This configuration requires the Veritas Volume Manager (VxVM version 3.2 or later) with the VVR license.

FlashBackup and alternate client combination example

FlashBackup is a policy type that combines the speed of raw-partition backup with the ability to restore individual files. FlashBackup can be combined with

38 Introduction

Off-host backup methods off-host backup methods, such as alternate client backup in the split-mirror configuration.

Figure 1-12 Alternate client split-mirror backup with FlashBackup policy type

NetBackup master server

LAN / WAN primary client

(Detail from policy attributes dialog.) alternate client media server primary disk mirror disk storage

The figure shows the following phases:

Phase

Phase 1

Phase 2

Phase 3

Phase 4

Phase 5

Phase 6

Action

Mirror disk is synchronized with primary.

Primary client collaborates with the alternate client to create the snapshot, splitting the mirror disk from primary disk and mounting the snapshot on the alternate client.

Alternate client creates file system map of the snapshot.

Alternate client sends the file system map to the media server.

Alternate client streams the snapshot-based backup from the mirror to the media server.

Media server reads the backup image from the alternate client.

Introduction

Off-host backup methods

39

Phase

Phase 7

Action

Media server writes the backup image to storage.

NetBackup Media Server data mover example (UNIX only)

In this off-host backup method, a NetBackup media server reads the backup data from the client snapshot and writes the data to a storage device. The NetBackup media server uses the mapping information that the client provides to read the data as raw disk extents (units consisting of physical address and length). This method is not supported for Windows clients.

This mapping-based data movement is in addition to the normal backup processing that the media server performs in a master server/media server configuration.

Note: For a multi-ported SCSI disk array, a Fibre Channel SAN is not required.

Figure 1-13 NetBackup Media Server data mover

NetBackup master server

(Detail from policy attributes dialog.)

LAN / WAN client media server

Fibre Channel/SAN robot on

SAN disks of client data on SAN

The figure shows the following phases in the backup process:

40 Introduction

Off-host backup methods

Phase

Phase 1

Phase 2

Phase 3

Phase 4

Action

On LAN, NetBackup master server tells the client to map the snapshot data on the disk.

On LAN, client sends the mapping information to the media server.

Media server processes the mapping information and reads client data over the SAN, from the addresses that the client provides.

Media server writes data across the SAN to storage.

About the NDMP Data Mover

Replication Director enables NetBackup to use NDMP to perform the following operations:

■ Restore from snapshot backups.

■ Perform a live browse of snapshots.

■ Restore from snapshots for the copy back method.

Support for all these operations is provided for replicated snapshots as well.

Configuring a policy to use NDMP with Replication Director

To configure a policy to use NDMP with Replication Director, the following

Snapshot Client options must be set in the backup policy. To set the options:

■ Select Perform off-host backup.

■ Select Data Mover from the Use drop-down menu.

■ Select NDMP from the Machine drop-down menu.

Figure 1-14 NDMP policy for snapshot replication

Introduction

Snapshot Client requirements

41

For more information about configuring a policy to use NDMP with Replication

Director, see the NetBackup Replication Director Solutions Guide.

Snapshot Client requirements

NetBackup Snapshot Client requires the following components:

■ A master server with NetBackup Snapshot Client server software installed.

■ Clients running Solaris, HP, AIX, Linux, or Windows, with NetBackup Snapshot

Client software installed.

Certain operating system and device patches (such as for the host bus adapter) may be required for both servers and clients.

See

“Snapshot Client assistance”

on page 47.

Please note the following additional requirements:

■ For the VxFS_Checkpoint snapshot method, all clients must have VxFS 3.4 or later with the Storage Checkpoints feature.

■ To use Snapshot Client to back up a VxFS file system, the client’s VxFS file system has to be patched with the dynamic linked libraries.

■ For the VxVM snapshot method, all clients must have VxVM 3.1 or later.

■ For the FlashSnap and VVR snapshot methods, all clients must have VxVM

3.2 or later. Each method requires its own add-on license to VxVM.

■ For the disk array snapshot methods, assistance may be required from the disk array vendor.

■ To use the snapshot and off-host backup features of NetBackup Snapshot

Client with a NetBackup Oracle policy, UNIX clients must have Oracle8i or later installed.

■ HP clients must use the Online JFS file system, not the default JFS.

Snapshot Client restrictions

For detailed support information, refer to the following:

■ For a complete list of supported platforms, snapshot methods, data types, and database agents, including all supported combinations of platform and snapshot methods, see the NetBackup 7.x Snapshot Client Compatibility document: http://www.symantec.com/docs/TECH126901

■ Further information is also available.

See

“Snapshot Client assistance”

on page 47.

Note the following restrictions:

42 Introduction

Snapshot Client requirements

■ Snapshot Client does not support the ALL_LOCAL_DRIVES entry in the policy’s

Backup Selections list.

■ The VxFS_Checkpoint and VxVM snapshot methods support VxFS multi-volume file systems only.

■ For the NetBackup Media Server or Third-Party Copy Device methods, the client disk must be either a SCSI or Fibre Channel device.

■ For off-host backup that use a Data Mover with the nbu_snap,

VxFS_Checkpoint, or VxVM snapshot methods: the NetBackup media server must have access to all the disks that make up the snapshot. The disk(s) can be connected to a SAN. For each of these snapshot methods, note the following:

■ nbu_snap: media server requires access to the active disk and the cache disk.

■

■

VxFS_Checkpoint: media server requires access to the primary or active disk.

VxVM: access requirements depend on layout of the volume group. Media server must be able to access all disks that make up the snap mirror volume.

■ For off-host backups that use the NDMP Data Mover option to replicate snapshots, see the Replication Director Solutions Guide for a list of limitations.

■ In a clustered environment, Instant Recovery point-in-time rollback is not supported for backups that were made with a disk array snapshot method.

The disk array snapshot methods are described in the chapter titled

Configuration of snapshot methods for disk arrays.

See

“About the new disk array snapshot methods”

on page 181.

■ For the TimeFinder, ShadowImage, or BusinessCopy legacy snapshot methods

(when using the NetBackup Media Server or Third-Party Copy Device backup methods): the NetBackup clients must have access to the mirror (secondary) disk containing the snapshot of the client’s data. The NetBackup clients must also be able to access the primary disk. The NetBackup media server only needs access to the mirror (secondary) disk.

■ For the TimeFinder, ShadowImage, or BusinessCopy legacy snapshot methods, a Volume Manager disk group must consist of disks from the same vendor.

■ The NetBackup Media Server off-host backup method does not support clients that use client deduplication. If the client is enabled for deduplication, you must select Disable client-side deduplication on the policy Attributes tab.

■ For the NetBackup Media Server or Third-Party Copy Device backup method: the disk must return its SCSI serial number in response to a serial-number inquiry (serialization), or the disk must support SCSI Inquiry Page Code 83.

Introduction

Snapshot Client terminology

43

■ Multiplexing is not supported for Third-Party Copy Device off-host backups.

■ For alternate client backup: the user and group identification numbers (UIDs and GIDs) for the files must be available to the primary client and the alternate backup client.

■ Inline Tape Copies (called Multiple Copies in Vault) is not supported for

Third-Party Copy Device off-host backups.

■ For media servers running AIX (4.3.3 and higher), note the following:

■ Clients must be Solaris, HP, or AIX.

■ Requires the use of tape or disk LUNs to send the Extended Copy commands for backup.

■

■

The tape must be behind a third-party-copy-capable FC-to-SCSI router, and the router must be able to intercept Extended Copy commands sent to the tape LUNs.

The mover.conf

file must have a tape path defined, not a controller path.

Snapshot Client terminology

Table 1-5

describes terms that are used with NetBackup Snapshot Client. For explanations of other NetBackup terms, consult the NetBackup online glossary.

Table 1-5 Snapshot Client terminology

Term

Alternate Client Backup

Definition

The alternate client performs a backup on behalf of another client.

Backup agent (see also

Third-Party Copy Device)

A general term for the host that manages the backup on behalf of the NetBackup client.

The agent is either another client, the NetBackup media server, a third-party copy device, or a NAS filer.

BCV The mirror disk in an EMC primary-mirror array configuration (see mirror). BCV stands for Business Continuance Volume.

Bridge In a SAN network, a bridge connects SCSI devices to Fibre Channel. A third-party copy device can be implemented as part of a bridge or as part of other devices. Note that not all bridges function as third-party copy devices.

44 Introduction

Snapshot Client terminology

Term

Cache

Copy manager

Copy-on-Write

Data movement

Data mover device

Disk group

Extent

FastResync (VxVM)

Fibre Channel

Table 1-5 Snapshot Client terminology (continued)

Definition

Copy-on-write snapshot methods need a separate working area on disk during the lifetime of the snapshot. This area is called a cache. The snapshot method uses the cache to store a copy of the client’s data blocks that are about to change because of file system activity. This cache must be a raw disk partition that does not contain valuable information: when using the cache, the snapshot method overwrites any data currently stored there.

See

“How copy-on-write works”

on page 312.

See Third-Party Copy Device.

In NetBackup Snapshot Client, one of two types of supported snapshots (see also mirror).

Unlike a mirror, a copy-on-write does not create a separate copy of the client’s data. It creates a block-by-block "account" from the instant the copy-on-write was activated.

The account describes which blocks in the client data have changed and which have not. The backup application uses this account to create the backup copy. Other terms and trade names sometimes used for copy-on-write snapshots are space-optimized snapshots, space-efficient snapshots, and checkpoints.

A copy operation as performed by a third-party copy device or NetBackup media server.

The host or entity that manages the backup on behalf of the NetBackup client. The data mover can be either the NetBackup media server, a third-party copy device, or a NAS filer.

A general term for any of the following: LUN, logical volume, vdisk, and BCV or STD.

A configuration of disks to create a primary-mirror association, using commands unique to the disks’ vendor. See mirror and volume group.

A contiguous set of disk blocks that are allocated for a file and represented by three values: device identifier, starting block address (offset in the device) and length (number of contiguous blocks). The mapping methods in Snapshot Client determine the list of extents and send the list to the backup agent.

Formerly known as Fast Mirror Resynchronization or FMR, VxVM FastResync performs quick and efficient resynchronization of mirrors. NetBackup’s Instant Recovery feature uses FastResync to create and maintain a point-in-time copy of a production volume.

A type of high-speed network that is composed of either optical or copper cable and employing the Fibre Channel protocol. NetBackup Snapshot Client supports both arbitrated loop and switched fabric (switched Fibre Channel) environments.

Introduction

Snapshot Client terminology

45

Term

File system

Instant Recovery

Mapping

Mapping methods

Mirror

Table 1-5 Snapshot Client terminology (continued)

Definition

Has two meanings. Regarding a product, such as UFS (Sun Solaris) or VxFS (Veritas) file systems, file system means the management and allocation schemes of the file tree.

Regarding a file tree component, file system means a directory that is attached to the

UNIX file tree by means of the mount command. When a file system is selected as an entry in the NetBackup Backup Selections list, this definition applies.

A restore feature of a disk snapshot of a client file system or volume. Client data can be rapidly restored from the snapshot, even after a system reboot.

Converting a file or raw device (in the file system or Volume Manager) to physical addresses or extents for backup agents on the network. NetBackup Snapshot Client uses the VxMS library to perform file mapping.

A set of routines for converting logical file addresses to physical disk addresses or extents. NetBackup Snapshot Client includes support for file-mapping and volume-mapping methods.

Has two meanings.

■

■

A disk that maintains an exact copy or duplicate of another disk. A mirror disk is often called a secondary, and the source disk is called the primary. All writes to the primary disk are also made to the mirror disk.

A type of snapshot that is captured on a mirror disk. At an appropriate moment, all further writes to the primary disk are held back from the mirror, which "splits" the mirror from the primary. As a result of the split, the mirror becomes a snapshot of the primary. The snapshot can then be backed up.

NetBackup Media Server method

Off-host backup

An off-host backup method in which the NetBackup media server performs the data movement.

Primary disk

The off-loading of backup processing to a separate backup agent executing on another host. NetBackup Snapshot Client provides the following off-host backup options:

Alternate Client, NetBackup Media Server, Third-Party Copy Device, and Network

Attached Storage.

In a primary-mirror configuration, client applications read and write their data on the primary disk. An exact duplicate of the primary disk is the mirror.

Raw partition A single section of a raw physical disk device occupying a range of disk sectors. The raw partition does not have a file system or other hierarchical organization scheme

(thus, a "raw" stream of disk sectors). On some operating systems, such as Solaris and

HP-UX, a raw partition is different from a block device over which the file system is mounted.

Recovery Manager (RMAN) Oracle's backup and recovery program. RMAN performs backup and restore by making requests to a NetBackup shared library.

46 Introduction

Snapshot Client terminology

Term

RMAN Proxy Copy

SAN (Storage Area

Network)

Table 1-5 Snapshot Client terminology (continued)

Definition

An extension to the Oracle8i Media Management API which enables media management software such as NetBackup to perform data transfer directly.

A Fibre Channel-based network connecting servers and storage devices. The storage devices are not attached to servers but to the network itself, and are visible to all servers on the network.

Secondary disk

Snapshot

Snapshot method

Snapshot mirror

Snapshot source

Snapshot Volume

See mirror.

A point-in-time, read-only, disk-based copy of a client volume. A snapshot is created with minimal impact on other applications. NetBackup provides several types, depending on the device where the snapshot occurs: copy-on-write, mirror, clone, and snap.

A set of routines for creating a snapshot. You can select the method, or let NetBackup select it when the backup is started (auto method).

A disk mirror created by the Veritas Volume Manager (VxVM). Snapshot mirror is an exact copy of a primary volume at a particular moment, reproduced on a physically separate device.

The entity (file system, raw partition, or logical volume) to which a snapshot method is applied. NetBackup automatically selects the snapshot source according to the entries in the policy’s Backup Selections list.

A mirror that has been split from the primary volume or device and made available to users. Veritas Volume Manager (VxVM) creates snapshot volumes as a point-in-time copy of the primary volume. Subsequent changes in the primary volume are recorded in the Data Change Log. The recorded changes can be used to resynchronize with the primary volume by means of VxVM FastResync. The changes that were made while the snapshot volume was split are applied to the snapshot volume to make it identical to the primary volume.

Standard device Refers to the primary disk in an EMC primary-mirror disk array (see primary disk).

Storage Checkpoint (VxFS) Provides a consistent and stable view of a file system image and keeps track of modified data blocks since the last checkpoint. Unlike a mirror, a VxFS Storage Checkpoint does not create a separate copy of the primary or original data. It creates a block-by-block account that describes which blocks in the original data have changed from the instant the checkpoint was activated.

A Storage Checkpoint stores its information in available space on the primary file system, not on a separate or designated device. (Also, the ls command does not list

Storage Checkpoint disk usage; you must use the fsckptadm list command instead.)

Introduction

Snapshot Client assistance

47

Term

Third-Party Copy Device

Table 1-5

Definition

Snapshot Client terminology (continued)

Has two meanings:

■

■

A backup agent on the SAN that operates on behalf of backup applications. The third-party copy device receives backup data from a disk that is attached to Fibre

Channel and sends it to a storage device. The third-party copy device uses the SCSI

Extended Copy command. The third-party copy device is sometimes called a copy manager, third-party copy engine, or data mover. In SAN hardware configurations, a third-party copy device can be implemented as part of a bridge, router, or storage device. The third-party copy device may or may not be the device to which the storage units are connected.

An off-host backup method in NetBackup Snapshot Client that allows backups to be made by means of a backup agent on the SAN.

UFS file system

VxMS (Veritas Federated

Mapping Services)

A library of routines (methods) used by NetBackup Snapshot Client to obtain the physical addresses of logical disk objects such as files and volumes.

Volume

The UNIX File System (UFS), which is the default file system type on Sun Solaris. The

UFS file system was formerly the Berkeley Fast File System.

Volume group

A virtual device that is configured over raw physical disk devices (not to be confused with a NetBackup Media and Device Management volume). Consists of a block and character device. If a snapshot source exists over a volume, NetBackup automatically uses a volume mapping method to map the volume to physical device addresses.

A logical grouping of disks, created with the Veritas Volume Manager, to allow more efficient use of disk space.

VxFS

VxVM

FIM

The Veritas extent-based File System (VxFS), designed for high performance and large volumes of data.

The Veritas Volume Manager (VxVM), which provides logical volume management that can also be used in SAN environments.

Frozen Image Method., see OST_FIM.

Snapshot Client assistance

The following kinds of assistance are available.

48 Introduction

About open file backups for Windows

Table 1-6 Types of assistance available for Snapshot Client

Type of assistance Description

Snapshot Client help from

NetBackup Administration

Console

For help creating a policy, click the Master Server name at the top of the left pane and click Create a Snapshot Backup Policy.

Snapshot Client assistance from the Web

For a document containing additional Snapshot Client assistance, see the tech note

NetBackup Snapshot Client Configuration. This document may be accessed from the following link: http://www.symantec.com/docs/TECH51377

This document includes the following:

■

■

■

An up-to-date list of supported operating systems and peripherals

Detailed configuration assistance for the legacy disk array snapshot methods:

EMC TimeFinder, Hitachi ShadowImage, and HP BusinessCopy

Sections on SAN device configuration and on setting up NetBackup for off-host data mover backups (with instructions for creating 3pc.conf and mover.conf

files)

Compatibility list

NDMP information on the

Web

For a complete list of supported platforms, snapshot methods, data types, and database agents, including all supported combinations of platform and snapshot methods, see the NetBackup 7.x Snapshot Client Compatibility document: http://www.symantec.com/docs/TECH126901

The Symantec support web site has a pdf document on supported NDMP operating systems and NAS vendors. The document also contains configuration and troubleshooting help for particular NAS systems.

This document may be accessed from the following link: http://www.symantec.com/docs/TECH31885

The document’s title is: NetBackup for NDMP Supported OS and NAS Appliance

Information.

About open file backups for Windows

The Open File Backup license is included in the standard NetBackup for Windows product, and enables open file backups of Windows clients. Open File Backup is independent of Snapshot Client. The Snapshot Client product is not required for

Windows open file backups.

See the NetBackup Administrator’s Guide, Volume I.