Celerra Glossary

EMC ® Celerra ® Network Server
Release 6.0
P/N 300-009-954
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Published September 2010
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Celerra Glossary 6.0
Celerra Glossary 6.0
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Celerra Glossary 6.0
As part of an effort to improve and enhance the performance and capabilities of its product
line, EMC periodically releases revisions of its hardware and software. Therefore, some
functions described in this EMC® Celerra® Glossary may not be supported by all revisions
of the software or hardware currently in use. For the most up-to-date information on
documentation and product features, refer to your product release notes on the EMC
Powerlink® website.
If a product does not function properly or does not function as described in the Celerra
Glossary, please contact your EMC Customer Support Representative.
This document is part of the Celerra Network Server documentation set, and is intended
for use by system administrators during installation and setup of the product.
This is a glossary of network-attached storage (NAS) terminology used in reference to
the Celerra Network Server product line. Terms specific to a particular product are
designated as such in the definition.
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Celerra Glossary 6.0
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Celerra Glossary 6.0
access-based enumeration (ABE)
With ABE enabled, Windows will not display files or folders that the user does not have the
rights to access. Only those files or folders that the user has the rights to access are visible,
thus increasing folder-level security.
access control entry (ACE)
In a Microsoft Windows environment, an element of an access control list (ACL). This element
defines access rights to a file for a user or group.
access control levels
Entries in an access control level table created and recognized only in the Control Station
database that define the access level allowed for specified administrative users. These entries
are used in conjunction with an access control value associated with certain system objects
to define administrative user access to EMC Celerra® system objects.
access control list (ACL)
List of access control entries (ACEs) that provide information about the users and groups
allowed access to an object.
access policy
Policy that defines which access control methods (NFS permissions or Windows ACLs or
both) are enforced when a user accesses a file on a Celerra system in an environment
configured to provide multiprotocol access to some filesystems. The access policy is set with
the server_mount command and also determines which actions a user can perform against
a file or directory.
access privileges
Extent to which a user may operate a system resource on a network or file server. In many
cases, permission to access a server, view its contents, and modify or create files is limited
by the network's system administrator in order to maintain security.
See access control entry.
See access control list.
Celerra Glossary 6.0
For EMC Symmetrix® Remote Data Facility (SRDF®) or EMC MirrorView™/Synchronous
configurations, a bidirectional configuration with two production sites, each acting as the
standby for the other. Each Celerra Network Server has both production and standby Data
Movers. If one site fails, the other site takes over and serves the clients of both sites. For
SRDF, each Symmetrix storage system is partitioned into source (production) and remote
destination volumes. For MirrorView/S, each EMC CLARiiON® storage system is configured
to have source and destination LUNs and a consistency group.
Active Directory (AD)
Advanced directory service included with Windows operating systems. It stores information
about objects on a network and makes this information available to users and network
administrators through a protocol such as Lightweight Directory Access Protocol (LDAP).
Active Directory Users and Computers (ADUC)
Administrative tool designed to perform day-to-day Active Directory administration tasks.
These tasks include creating, deleting, modifying, moving, and setting permissions on objects
stored in the directory. These objects include organizational units, users, contacts, groups,
computers, printers, and shared file objects.
active NDMP backup/restore streams
The number of NDMP backup or restore streams that are currently active.
For SRDF or MirrorView/S configurations, a unidirectional setup where one Celerra, with
its attached storage system, serves as the source (production) file server and another Celerra,
with its attached storage, serves as the destination (backup). This configuration provides
failover capabilities in the event that the source site is unavailable. An SRDF configuration
requires Symmetrix systems as backend storage. A MirrorView/S configuration requires
specific CLARiiON CX series systems as backend storage.
active replication session
Replication session that is transferring the delta from source to destination site.
adapter card
Circuit board that provides the physical interface between devices.
adaptive copy disk-pending mode
SRDF mode of operation in which write tasks accumulate in global memory on the local
system before being sent to the remote system. This mode allows the primary and secondary
volumes to be more than one I/O out of synchronization. The maximum number of I/Os that
can be out of sychronization is defined using a maximum skew value.
adaptive copy write-pending mode
SRDF mode of operation in which write tasks accumulate on the primary volume rather
than in global memory. A background process destages write tasks to the corresponding
destination volumes. Disk mode consumes less global memory, however, transfers are
typically slower due to reads coming from disk instead of memory.
Celerra Glossary 6.0
Address Resolution Protocol (ARP)
Protocol that translates IP addresses to MAC addresses.
administrative shares
Microsoft term for c$, d$, and so forth that is the automatically shared root level of the file
system. Windows maintains default administrative shares that are created for Windows
partitions and other system folders. The shares have a dollar sign ($) suffix, are invisible to
network browsing, and are only accessible to accounts with administrator, backup operator,
or server operator privileges on the particular system.
See Alternate data stream.
See Active Directory Users and Computers.
Software executable that performs specific actions, often in concert with other system
In Unisphere software, a system event that requires administrative attention. These events
may be severe enough to cause a system error or disrupt user access.
Alternate data stream (ADS)
Alternate data stream allows files to be associated with more than one data stream. For
example, a file such as text.txt can have an ADS with the name of text.txt:secret (of form
filename:streamname) that can only be accessed by knowing the ADS name or by specialized
directory browsing programs.
append-only state
State of a file when the data in it cannot be modified, but the file can have new data appended
to the end of it. In addition, the file itself cannot be deleted. Once a file in the append-only
state has been written to, changing it to the locked state by making it read-only locks it into
that state until its retention date has passed.
See application programming interface.
application programming interface (API)
Mechanism used to communicate between programs. One program uses the function calls
in the API of another program to access its operations.
See Address Resolution Protocol.
ASCII (American Standard Code for Information Interchange)
7-bit (one byte) character-encoding scheme for representing text and controlling printers
and computer communication based on the ordering of the English alphabet. US-ASCII was
the most commonly used character encoding on the Internet until it was recently surpassed
by UTF-8. ASCII was incorporated into the Unicode character set as the first 128 symbols,
so the ASCII characters have the same numeric codes in both sets.
Process for verifying the identity of a user trying to access a resource, object or service, such
as a file or a directory.
Process of granting access permission to a system resource to a user based on his or her
identity. For example, grant a user backup administration privileges.
automated backup and restore
Procedure in which a remote backup server running NDMP-compliant backup software
backs up data to a tape library unit (TLU).
See also local backup and remote backup.
automatic file system extension
Configurable Celerra file system feature that automatically extends a file system created or
extended with AVM when the high water mark (HWM) is reached.
See also high water mark.
Automatic Volume Management (AVM)
Feature of the Celerra Network Server that creates and manages volumes automatically
without manual volume management by an administrator. AVM organizes volumes into
storage pools that can be allocated to file systems.
See also Virtual Provisioning.
AV engine
Third-party antivirus software running on a Windows Server that works with the Celerra
AntiVirus Agent (CAVA).
See also AV server, CAVA, VC client, and virus definition file.
See Automatic Volume Management.
AV server
Windows Server configured with the CAVA and a third-party antivirus engine.
See also AV engine, CAVA, and VC client.
AV user
Specific domain user either created or selected as the account configured for the virus
checking. Use this account when configuring all of the Windows Servers with CAVA and
the AV engine.
Celerra Glossary 6.0
Interconnecting device that may or may not have intelligence, but usually has sockets into
which circuit boards are plugged.
backup and restore
Technique for ensuring file system integrity and security by backing up to tape or disk a
file system or incremental changes to a file system. This data can be restored later.
backup domain controller (BDC)
Windows NT domain controller that has the same database as the primary domain controller
(PDC) and may replace the PDC if needed.
Maximum amount of data that can be transmitted through a data channel per unit of time.
Usually expressed in megabytes per second.
bandwidth aggregation
See Ethernet channel.
bandwidth schedule
List of time periods (days and hours) and bandwidth values (in KB/s) that control the amount
of bandwidth available for a given Data Mover interconnect.
baseline checkpoint
Read-only checkpoint from which a writeable checkpoint is created.
basic input-output system (BIOS)
Essential set of routines stored on a chip. It provides a standard interface between the
operating system and vendor-specific hardware.
battery backup unit
Celerra cabinet component that provides 3 minutes of battery power to the cabinet during
a power outage.
See business continuance volume.
Celerra Glossary 6.0
See backup domain controller.
Software register that tracks if a Production File System (PFS) block has changed since the
latest checkpoint was created.
See also production file system.
See basic input-output system.
See Data Mover.
Data structure that maps the older PFS volume block saved to the SavVol block. Each
checkpoint has a blockmap and is pageable to the SavVol from the Data Mover memory.
See also production file system and PFS.
blockmap index file
On-disk representation of a checkpoint’s blockmap stored with each checkpoint on the
Units of storage (8 KB each) that comprise a file system.
Component of the Celerra Control Station that supports the high-availability feature by
monitoring the Celerra system hardware components to detect their presence and current
state or their absence.
Device that provides a nonswitching connection between two or more local area networks
Data frame or packet transmitted to every node on the local network segment.
broadcast domain
Group of entities on the network able to communicate with one another without going
through a router.
Browse Master
Microsoft Windows service that gathers and organizes the list of computers and domains
displayed in Network Neighborhood. The Browse Master maintains an up-to-date list of
network resources and provides this information to other network computers.
Program used to access information over the Internet or an intranet.
Celerra Glossary 6.0
Bits per second (b/s).
Bytes per second (B/s).
Storage area used for handling data in transit. Buffers compensate for differences in
processing speed between source and destination.
See Ethernet channel.
business continuance volume (BCV)
Symmetrix volume used as a mirror that attaches to and fully synchronizes with a production
(source) volume on the Celerra Network Server. The synchronized BCV is then separated
from the source volume and is addressed directly from the host to serve in backup and
restore operations, decision support, and application testing.
Celerra Glossary 6.0
Temporary storage used to retain frequently used data for faster access. For example, a
memory cache may be used between a CPU and main memory.
Celerra Network Server uses its telephone modem to automatically notify EMC or your
service provider when certain problems are detected. Problems that trigger a CallHome
include hardware failures, high temperature in the cabinet, and some software errors.
See Celerra AntiVirus Agent.
CAVA Calculator
Tool that estimates the number of CAVAs required to provide a user-defined level of
performance in a CAVA pool, based on user information. The tool can be run at any time,
even if there is no CAVA present.
CAVA sizing tool
Program that monitors all CAVAs in the network, and sizes the network to find the ideal
number of AV servers. When you install CAVA on the AV servers, the CAVA sizing tool,
cavamon.exe, is also installed.
See command descriptor block.
See Celerra Data Migration Service.
Celerra AntiVirus Agent (CAVA)
Application developed by EMC that runs on a Windows Server and communicates with a
standard antivirus engine to scan CIFS files stored on a Celerra Network Server.
See also AV engine, AV server, and VC client.
Celerra Glossary 6.0
Celerra Data Migration Service (CDMS)
Feature for migrating file systems from NFS and CIFS source file servers to a Celerra Network
Server. The online migration is transparent to users once it starts.
Celerra Event Enabler
Framework that provides the working environment for the CAVA and CEPA facilities.
Celerra Event Publishing Agent (CEPA)
EMC-provided agent running on a Windows Server that provides details of events occurring
on the Windows server. It can communicate with the Celerra Network Server to display a
list of events that occurred.
Celerra FileMover
Policy-based system used to determine where files should be physically stored. In most
cases, policies are based on file size or last access time (LAT) or both and are used to identify
data that can be moved to slower, less-expensive storage.
Celerra FileMover API
API that enables integration between the Celerra Network Server and policy and archiving
software applications to automatically monitor and manage the movement of files between
primary and secondary storage.
Celerra Monitor
Java client/server application that lets an administrator observe the performance of a storage
system attached to a Celerra Network Server and the performance of any Data Movers
mounted in the Celerra Network Server cabinet.
Celerra MPFS over iSCSI
Multi-Path File System over iSCSI-based clients. MPFS client running an iSCSI initiator
works in conjunction with an IP-SAN switch containing an iSCSI to SAN blade. The IP-SAN
blade provides one or more iSCSI targets that transfer data to the storage area network
(SAN) storage systems.
See also Multi-Path File System (MPFS).
Celerra Network Server
EMC network-attached storage (NAS) product line.
See Celerra Event Publishing Agent.
Mechanism used by consumer applications to register for, receive, and act on events taking
place in the Celerra CIFS file systems.
Certificate Authority (CA)
Trusted third-party that creates and digitally signs public key certificates.
Certificate Authority Certificate
Digitally signed association between an identity (Certificate Authority) and a public key to
be used by the host to verify digital signatures on Public Key Certificates.
Celerra Glossary 6.0
See Common Gateway Interface.
Challenge Handshake Authentication (CHAP)
Access control protocol for secure authentication using shared passwords called secrets.
channel director
Component in a Symmetrix system that connects the host channels and data storage. It
transfers data between the channel and cache.
See Challenge Handshake Authentication Protocol.
character encoding
The mapping from a coded character set to a sequence of bits.
character set
Set of characters used by a language (ANSI/ASCII or Unicode). The character set affects file
format (how the software stores and transmits data) and string processing (the logic with
which text is manipulated).
Point-in-time, logical image of a PFS. A checkpoint is a file system and is also referred to as
a checkpoint file system or an EMC SnapSure™ file system.
See also production file system.
checkpoint application
Business application that reads a checkpoint for point-in-time information about a PFS.
Checkpoint applications require point-in-time data, but not realtime data.
See also production file system.
checkpoint audit
Process of monitoring the SavVol to determine how much free space remains for capturing
checkpoint data. By default, SnapSure automatically audits the SavVol and writes a message
to the system log when the SavVol’s high water mark (HWM) is reached.
checkpoint refresh
Process of recycling the SavVol space by deleting a PFS checkpoint data and creating a new
checkpoint by using the same checkpoint filename, file system identification number, and
mount state.
checkpoint restore
Process of restoring a PFS to a point in time by using a checkpoint. As a precaution, SnapSure
automatically creates a new checkpoint of the PFS before it performs a restore operation.
See also production file system.
Checkpoint Virtual File System (CVFS)
File system that allows an NFS or a CIFS client read-only access to online snapshots of a file
system directory by accessing a virtual .ckpt directory entry. CVFS and SVFS are synonymous
checkpoint window
Length of time a checkpoint is active, beginning when the checkpoint is created and ending
when the checkpoint’s SavVol is full or the checkpoint is deleted.
See Common Internet File System.
CIFS server
Logical server that uses the CIFS protocol to transfer files. A Data Mover can host many
instances of a CIFS server. Each instance is referred to as a CIFS server.
CIFS service
CIFS server process that is running on the Data Mover and presents shares on a network as
well as on Microsoft Windows-based computers.
EMC midrange block storage system.
CLEAN state
See not locked state.
See command line interface.
Front-end device that requests services from a server, often across a network.
clock offset
Difference between the local system time and the time retrieved from the time server.
command descriptor block (CDB)
SCSI term for a fixed block of data transmitted as a single entity. A CDB is a SCSI packet.
command line interface (CLI)
Interface for typing commands through the Control Station to perform tasks that include
the management and configuration of the database and Data Movers and the monitoring
of statistics for the Celerra cabinet components.
common base
Internal checkpoint that is common on both replication source and destination site and is
used as a base in the next differential data transfer.
Common Gateway Interface (CGI)
Standard for interfacing an external application with an information server, such as HTTPS.
Celerra Glossary 6.0
Common Internet File System (CIFS)
File-sharing protocol based on the Microsoft Server Message Block (SMB). It allows users
to share file systems over the Internet and intranets.
component file system
File system mounted on the nested mount root file system that is part of the nested mount
file system.
configured replication session
Replication session that is idle, active, or inactive. A stopped replication session is not a
configured session.
Celerra CallHome file delivery system with multitransport and failover support.
connection database
Database of secondary storage connection information that includes the server name, share,
and credentials, which are stored on the file and maintained across system reboots.
Ability of hardware devices or software to communicate with other hardware or software.
Control Station
Hardware and software component of the Celerra Network Server that manages the system
and provides the user interface to all Celerra components.
coordinated universal time (UTC)
Formerly Greenwich Mean Time (GMT), UTC is the international time standard.
See Cyclic Redundancy Check.
See customer-replaceable unit.
cumulative incremental backup
Backup that copies all data modified since the last full backup. To restore data when
cumulative incremental backups are in use, you need only the latest full and cumulative
incremental backups.
See also differential backup, differential incremental backup, full backup, and incremental backup.
customer-replaceable unit (CRU)
On a CLARiiON system, hardware a customer can add or replace while the disk-array
enclosure (DAE) is powered up. Examples of CRUs include power supplies and drive fan
packs. These components are also known as field-replaceable units (FRUs).
See Checkpoint Virtual File System.
Cyclic Redundancy Check (CRC)
Method used to perform additional error checking on the data sent over a Data Mover
interconnect to ensure data integrity and consistency. A CRC is a type of hash function used
to produce a checksum, a small fixed number of bits, against a block of data transferred to
a remote site. The checksum is used to detect errors after transmission. A CRC is computed
and appended before transmission and verified afterwards to confirm that no changes
occurred on transit.
Celerra Glossary 6.0
See discretionary access control list.
See Duplicate Address Detection.
See disk-array enclosure.
UNIX process that runs continuously in the background, but does nothing until it is activated
by another process or triggered by a particular event.
See direct access restore.
See data access in real time.
See direct access storage device.
data access in real time (DART)
On a Celerra system, the operating system software that runs on the Data Mover. It is a
realtime, multithreaded operating system optimized for file access, while providing service
for standard protocols.
data availability
Access to any and all user data by an application.
data element
An attribute in the Celerra system derived from a string.
Data Encryption Standard (DES)
Commonly used algorithm for encrypting and decrypting data.
Celerra Glossary 6.0
Data Mover
In a Celerra Network Server, a cabinet component that is running its own operating system
that retrieves data from a storage device and makes it available to a network client. This is
also referred to as a blade. A Data Mover is sometimes internally referred to as DART since
DART is the software that is running on the platform.
Data Mover Enclosure (DME)
In a Celerra Network Server, a shelf that includes an enclosure, one or two Data Movers,
management modules, and power and cooling modules.
Data Mover failover
Process started when an active Data Mover fails. The Control Station activates the failing
Data Mover’s standby replacement, if one is configured. The standby Data Mover takes the
identity of the failed Data Mover and continues processing requests. If a Data Mover has
multiple standbys, it will fail over only once from production to a standby. If the standby
fails, it will not fail over to another standby. Multiple active Data Movers can be associated
with a single standby Data Mover.
database management system (DBMS)
Software designed to manage databases. Data Movers use DBMS to create and manage
Usermapper and secmap mapping information.
Unit of data or packet transmitted in a TCP/IP network. A datagram contains source and
destination addresses and data.
See database management system.
See directory DAR.
See dynamic drive sharing.
Process used to compress redundant data, allowing space to be saved on a file system. When
multiple files have identical data, the file system stores only one copy of the data and shares
that data between the multiple files. Different instances of the file can have different names,
security attributes, and timestamps. None of the metadata is affected by deduplication.
default CIFS server
CIFS server created when you add a CIFS server and do not specify any interfaces (with the
interfaces= option of the server_cifs -add command). The default CIFS server uses all
interfaces not assigned to other CIFS servers on the Data Mover.
For Replication (V2), block changes to the source object, as calculated by comparing the
newest, currently marked internal checkpoint (point-in-time snapshot) against the previously
replicated internal checkpoint. Replication transfers these changes and applies them
immediately to the destination object, then refreshes the latest destination internal checkpoint.
Celerra Glossary 6.0
delta set
For SRDF/Asynchronous (SRDF/A), a predetermined cycle of operation used for
asynchronous host writes from a source to a destination. Each delta set contains groups of
I/Os for processing; the ordering of these I/Os are managed for consistency. For Celerra
Replicator, a set contains the block modifications made to the source file system that EMC
Celerra Replicator™uses to update the destination file system (read-only, point-in-time,
consistent replica of the source file system). The minimum delta-set size is 128 MB.
To unmount a snapshot from an iSCSI LUN. Upon demotion, the LUN is inaccessible and
changes made to the LUN while in a promoted state are lost.
dependent write consistency
For SRDF/A, the maintenance of a consistent point-in-time replica of data between a source
and destination through the processing and preservation of all writes to the destination in
ordered, numbered delta sets.
See Data Encryption Standard.
destination address
Hostname or IP address of the machine to which data is being sent.
destination Celerra
Term for the remote (secondary) Celerra Network Server in an SRDF or MirrorView/S
configuration. The destination Celerra is typically the “standby ? side of a disaster recovery
configuration. Symmetrix configurations often call the destination Celerra: the target Celerra.
Two types of devices are physical (port) and virtual.
See also virtual device.
device driver
Software component that provides the interface between a hardware device and the operating
device prefix
Indication of the type of network controller installed in the Celerra system.
See Microsoft Distributed File System.
See dynamic host configuration protocol.
System tests or firmware designed to inspect, detect, and correct failing components. These
tests are comprehensive and self-invoking.
differential backup
Backup that copies all data modified since the last full backup. To restore data when
differential backups are in use, you need only the latest full backup and the latest differential
See also cumulative incremental backup, differential incremental backup, full backup, and
incremental backup.
differential copy
The difference between the common base and the object that needs to be copied. Only the
delta between the common base and the source object is transferred to the destination.
differential incremental backup
Backup that copies data objects modified since the last full backup or incremental backup.
To restore data when differential incremental backups are in use, the newest full backup
and all subsequent differential backups are required.
See also cumulative incremental backup, full backup, and incremental backup.
iSCSI protocol error-checking method used to verify the integrity of an iSCSI packet header
(header digest) or payload data (data digest) using a checksum.
Digest Access Authentication
Means of verifying that the client and server possess a shared secret (a password).
digital certificate
Electronic ID issued by a certificate authority that establishes a user’s credentials. It contains
the user’s identity (a hostname), a serial number, expiration dates, a copy of the certificate
holder's public key (used for encrypting messages and digital signatures), and a digital
signature from the certificate-issuing authority so that a recipient can verify that the certificate
is valid.
direct access restore (DAR)
Data recovery operation that allows the NDMP client to directly access backed-up data
anywhere in a tape set without having to traverse the tape set sequentially.
direct access storage device (DASD)
Peripheral device that is directly addressable, such as a disk or drum. Typically used in a
mainframe environment.
Component in a Symmetrix system that allows it to transfer data between the host channels
and disk devices.
See also channel director and disk director.
directory database
See SAM.
Celerra Glossary 6.0
directory direct access restore (DDAR)
Improved form of DAR that supports directory-level DAR by restoring all the content under
the directory.
directory server
Server that stores and organizes information about a computer network's users and network
resources, and that allows network administrators to manage users' access to the resources.
X.500 is the best-known open directory service. Proprietary directory services include
Microsoft's Active Directory.
disaster recovery
Preventive measures using redundant hardware, software, data centers, and other facilities
to ensure a business can continue operations during a natural or man-made disaster and if
not, to restore business operations as quickly as possible afterward.
discretionary access control list (DACL)
User-specified (as opposed to system- or administrator-specified) functions.
disk-array enclosure (DAE2)
Shelf in a CLARiiON storage system that includes an enclosure, up to 15 disk modules, one
or two Fibre Channel link control cards (LCCs), and one or two power supplies, but does
not contain storage processors (SPs).
disk device
Physical disk or logical device in a storage subsystem viewed by client systems as a physical
disk director
Component in the Symmetrix system that interfaces between the cache and the disk devices.
disk group
Set of NS600 disk devices from which a disk volume is created. The type of a disk group is
specified by its storage profile.
On a Celerra system, a disk identification number.
disk processor enclosure (DPE2)
Shelf in a CLARiiON storage system that includes an enclosure, disk modules, storage
processors (SPs), Fibre Channel link control cards (LCCs), two power supplies, and fan
packs. A DPE supports DAEs in addition to its own disk modules.
disk volume
On Celerra systems, a physical storage unit as exported from the storage array. All other
volume types are created from disk volumes.
See also metavolume, slice volume, stripe volume, and volume.
See Data Mover Enclosure.
Oracle Direct NFS, a new feature in Oracle Database 11g, integrates the NFS client directly
with the Oracle software.
See Domain Name System.
Logical grouping of Microsoft Windows servers and other computers that share common
security and user account information. All resources such as computers and users are domain
members and have an account in the domain that uniquely identifies them. The domain
administrator creates one user account for each user in the domain, and the users log in to
the domain once. Users do not log in to each individual server.
domain controller
Server that authenticates user logins and maintains the security policy and the security
account’s master database for a Windows domain. Domain controllers manage user access
to a network, which includes logging in, authentication, and access to the directory and
shared resources.
See also Windows domain.
Domain Name System (DNS)
Name resolution software that allows users to locate computers on a UNIX network or
TCP/IP network by domain name. The DNS server maintains a database of domain names,
hostnames, and their corresponding IP addresses, and services provided by the application
See also ntxmap.
See disk processor enclosure.
Symmetrix system feature that automatically creates a backup data path to the disk devices
serviced directly by a disk director, should that disk director or the disk management
hardware for those devices fail.
Backup format in PAX that traverses a file tree in mixed width-first and depth-first order.
Duplicate Address Detection (DAD)
Means of determining if a new address is unique to the network.
dynamic drive sharing (DDS)
Feature of NDMP-compliant backup software that allows NDMP servers to share tape drives.
dynamic host configuration protocol (DHCP)
Software that automatically assigns temporary IP addresses to client stations logging in to
a TCP/IP network. It eliminates having to manually assign permanent IP addresses.
Celerra Glossary 6.0
dynamic load balancing
Distributes an I/O workload over all paths that different devices share.
See also load balancing and static load balancing.
dynamic sparing
Symmetrix system feature that automatically transfers data from a failing disk device to an
available spare disk device without affecting data availability. This feature supports all
nonmirrored devices in the Symmetrix subsystem.
Celerra Glossary 6.0
See EMC Data Manager.
EMC ControlCenter
Enterprise management software that allows an administrator to manage Symmetrix arrays
and other heterogeneous systems in an enterprise network.
EMC Data Manager (EDM)
Combination of software, hardware, and services that provides high-speed, centralized
backup and restore systems for enterprise-class data centers, optimized for Symmetrix and
Windows database environments.
emergency power-off box (EPO box)
Component in a Celerra system cabinet that contains six circuit breakers, one for each power
Mapping of individual characters in a character set to the specific bits used to represent the
data (used in protocol messages and how they are stored on disks).
See also Unicode and UTF-8.
Encoding data so it is readable only by specific users. Encrypted data is decoded by using
a special algorithm called a decryption key.
enterprise storage
Combination of intelligent storage systems, software, and services that together enable an
enterprise to store, retrieve, manage, protect, and share information from all major computing
environments, including UNIX, Windows, and mainframe platforms.
Enterprise Storage Network (ESN)
Combination of intelligent storage systems, software, and services. These products and
services together enable an enterprise to store, retrieve, manage, protect, and share
information from major computing environments, including UNIX, Windows, and mainframe
Celerra Glossary 6.0
EPO box
See emergency power-off box.
See Enterprise Storage Network.
See Ethernet channel.
Local area network (LAN) technology that transfers packets ranging from 48 bytes to 9000
bytes. Ethernet uses a media access method that listens before transmitting in order to
minimize packet collisions. Cable media and interface connectors supported on Celerra
systems include:
Network type
Cable media and interface connectors
10 Mb/s, thin-wire coaxial cable with BNC interface (up to
200 m)
10 Mb/s, thick-wire coaxial cable (up to 500 m)
10 Mb/s, hub (star) topology with twisted-pair drop cables
and RJ-45 interface
10 Mb/s, hub topology with optical fiber drop cables
100 Mb/s, two pairs of Category 5 unshielded twisted pair
(UTP) cable
(Fast Ethernet)
1 Gb/s, optical fiber cables (up to 550 m)
(Gigabit Ethernet)
Ethernet channel
High-availability feature that enables multiple active Ethernet connections to the same switch
to appear as a single link with a single MAC address and potentially multiple IP addresses.
EUC (Extended UNIX Code)
Multibyte character encoding system used primarily to represent Japanese, Korean, and
Simplified Chinese. The main alternatives to EUC encoding are JIS and more recently
Unicode, particularly in the form of UTF-8.
See extended unique identifier.
Celerra Glossary 6.0
System-generated message caused by a command, an error, or other condition that may
require action by an administrator. Events are typically written to an event log, and may
trigger an event notification.
event log
File of system-generated messages based on meeting a condition of a particular severity
level. There are separate event logs for the Control Station and for each physical and virtual
Data Mover in the system.
event notification
Process by which specified events meeting a severity threshold trigger an action or
See also notifications.
exclude file
Related to Celerra Data Migration Service (CDMS). Lists files and directories that should
not migrate from the source file server. Entries are removed on the Migration File System
(MGFS). All other files are migrated in an online state.
expired state
State of a file when its retention date has passed. A file in the expired state can be reverted
back to the locked state or deleted from the FLR-enabled file system, but cannot be altered.
File system or directory made available to NFS users on the network, or the process of
making a file system or directory available to NFS users on the network.
export mask
Masking of an NFS export to give access to only the user-specified hosts.
extended ACL
Container used to store extended attributes. In a Celerra FileMover system, extended ACLs
are used to back up and restore stub files through a CIFS network backup.
extended unique identifier (EUI)
IEEE naming standard supported by the iSCSI protocol. The format of EUI names is eui.
followed by an EUI-64 identifier.
Extensible Markup Language (XML)
Standards-based language intended to represent structured information.
Set of adjacent physical blocks.
Celerra Glossary 6.0
Fibre Channel topology structured with one or more switching devices that interconnect
Fibre Channel N_Ports and route Fibre Channel frames.
Component of a Celerra system that monitors the system and generates an event when a
certain condition is detected.
Process of immediately routing data to an alternate data path or device to avoid interrupting
services in the event of a failure. The impact to service is dependent on the application’s
ability to handle the change gracefully.
Fail-Safe Network (FSN)
High-availability feature that extends link failover out into the network by providing
switch-level redundancy. A FSN appears as a single link with a single MAC address and
potentially multiple IP addresses.
Fallthrough occurs when MPFS temporarily employs the NFS or CIFS protocol to provide
continuous data availability, reliability, and protection while block I/O path congestion or
unavailability is resolved. This fallthrough technology is seamless and transparent to the
application being used.
Fast Ethernet
Any Ethernet specification with a speed of 100 Mb/s. Based on the IEEE 802.3u specification.
See File Allocation Table.
See Fibre Backend Isolation.
Celerra Glossary 6.0
See Fibre Channel Arbitrated Loop.
See Fibre Channel Switch Fabric.
fiber optics
Communications systems that use optical fiber cables, which are composed of thin glass
strands designed for transmitting light.
Fibre Backend Isolation (FBI)
Feature used to help diagnose disk drive problems on a CLARiiON system.
Fibre Channel
Nominally 1 Gb/s data transfer interface technology, although the specification allows data
transfer rates from 133 Mb/s up to 4.25 Gb/s. Data can be transmitted and received
simultaneously. Common transport protocols, such as Internet Protocol (IP) and Small
Computer Systems Interface (SCSI), run over Fibre Channel. Consequently, a single
connectivity technology can support high-speed I/O and networking.
Fibre Channel Arbitrated Loop (FC-AL)
Standard for a shared access loop, in which a number of Fibre Channel devices are connected
(as opposed to point-to-point transmissions). Requires a port to successfully negotiate to
establish a circuit between itself and another port on the loop.
Fibre Channel Class 1 Service
Dedicated, uninterruptible connection designed for time-critical, continuous, dedicated
Fibre Channel Class 2 Service
Connectionless, packet-switched service with guaranteed delivery and confirmed receipt
of traffic.
Fibre Channel Class 3 Service
Connectionless service similar to packet-switched systems such as Ethernet in which the
path between two devices is not reserved or dedicated. Similar to Class 2, but without
delivery guarantee or confirmation mechanism. An American National Standards Institute
(ANSI) standard.
Fibre Channel Switch Fabric (FC-SW)
Fibre Channel network standard where nodes are connected to a fabric topology implemented
by one or more switches. Each node's N_Port connects to an F_Port on a switch. Pairs of
nodes connected to an FC-SW network can communicate concurrently.
field-replaceable unit (FRU)
Component replaced or added by service personnel as a single entity.
See also CRU.
Celerra Glossary 6.0
File Allocation Table (FAT)
File system used by MS-DOS and other Windows-based operating systems to organize and
manage files. The file allocation table (FAT) is a data structure that Windows creates when
you format a volume by using the FAT or FAT32 file systems. Windows stores information
about each file in the FAT so that it can retrieve the file later.
file-level retention (FLR)
FLR lets you store data on standard rewritable magnetic disks by using NFS or CIFS
operations to create a permanent, unalterable set of files and directories.
See also append-only state, expired state, locked state, not locked state, and retention date.
File Mapping Protocol (FMP)
File system protocol used to exchange file layout information between an application server
and the Celerra Network Server.
See also MPFS.
file server
Computer system that is optimized to serve files to clients. A file server does not run general
purpose applications. The Celerra Network Server refers to the complete system, which
includes several Data Movers and other components. The blocks of data that make up the
files served to clients are stored on the storage system.
file storage object
File created on an UxFS file system that provides the storage space for an iSCSI LUN.
file system
Method of cataloging and managing the files and directories on a storage system.
file system name
Unique identifier for a file system on a Celerra Network Server. There can be only one file
system with a particular name across all the Data Movers on the system.
See also share name.
file system quota
Configurable file system usage limit on the amount of data or the number of files created
on a file system, or the amount of data stored in a directory tree.
File Transfer Protocol (FTP)
High-level protocol for transferring files from one machine to another. Implemented as an
application-level program based on the OSI model, FTP uses the TCP protocol.
filter file
File that specifies the types of files to filter and the share on which files are filtered.
filtering for NDMP
Backup feature that allows administrators to specify using environmental variables in the
qualified backup vendor’s software, which directories and files within a file system to exclude
from the backup.
Embedded operating system in CLARiiON disk arrays.
See file-level retention.
FLR clock
Non-modifiable, per file system clock used to track the retention date. It is initialized when
an FLR-enabled file system is mounted read/write on a Data Mover. It does not advance
when a file system is unmounted or mounted read-only.
FLR state
See locked state.
See File Mapping Protocol.
See fully qualified domain name.
In communications, a fixed data block transmitted as a single entity. In local area networks
(LANs), the terms frame and packet are used synonymously.
See also packet.
frame tagging
Information added to a frame so the receiving device can identify the virtual local area
network (VLAN) to which it belongs. IEEE 802.3q is a frame-tagging standard.
Set of procedures, rules, and mechanisms for the development of an interface to multiple
instances of a type of system facility or component.
See field-replaceable unit.
See Fail-Safe Network.
See File Transfer Protocol.
full backup
Backup that copies a defined set of data, regardless of whether it has changed since the last
backup. A full backup is the basis from which incremental backups are taken.
See also cumulative incremental backup, differential incremental backup, and incremental backup.
fully qualified domain name (FQDN)
Full name of a system, which contains the domain name of the organization and its highest
Celerra Glossary 6.0
Logical disk used as a buffer between the Celerra Network Server and the Symmetrix storage
array for the exchange of management commands and data.
Celerra network server that is capable of connecting to multiple storage arrays, either directly
(direct-connected) or through a Fibre Channel switch (fabric-connected).
gateway address
Host or IP address of the gateway machine through which network traffic is routed.
See group identifier.
gigabit (Gb)
109 bits, defined as 2 to the 30th power (1,073,741,824) bits. One gigabit is equal to 1,024
Gigabit Ethernet
Any Ethernet specification with a speed of 1000 Mb/s. IEEE 802.3z defines Gigabit Ethernet
over fiber and cable, which has a physical media standard of 1000Base-X (1000Base-SX short
wave, 1000Base-LX long wave) and 1000Base-CX shielded copper cable. IEEE 802.3ab defines
Gigabit Ethernet over an unshielded twisted pair (1000Base-T).
gigabyte (GB)
109 bytes, defined as 2 to the 30th power (1,073,741,824) bytes. One gigabyte is equal to 1024
global group
In Windows NT, a global group contains only individual user accounts (no groups) from
the domain in which it is created. Once created, a global group can be assigned permissions
and rights, either in its own domain or in any trusting domain.
globalization (G11N)
The process of internationalizing and localizing software.
Celerra Glossary 6.0
See Group Policy Objects.
graphical user interface (GUI)
Software that uses graphical objects such as pull-down menus and operations such as
drag-and-drop to allow the user to enter commands and execute functions.
group identifier (GID)
Numeric identifier assigned to a particular group of users.
Group Policy Objects (GPO)
In Windows operating systems, administrators can use Group Policy to define configuration
options for groups of users and computers. Windows Group Policy Objects can control
elements such as local, domain, and network security settings.
See graphical user interface.
Celerra Glossary 6.0
hard quota
Configurable file system usage limit that, when reached, can cause the system to generate
an event or message and immediately deny user requests that would require more disk
space, such as creating or saving of files.
See also quota and soft quota.
See host bus adapter.
high water mark (HWM)
Trigger point at which the Celerra Network Server performs one or more actions, such as
sending a warning message, extending a volume, or updating a file system, as directed by
the related feature's software/parameter settings.
home directory
Special directory reserved for a particular user, it contains files and programs for the user.
In a Windows environment, the home directory is often specified in a user's profile so that
upon login, the home directory is automatically assigned to a network drive.
Addressable end node capable of transmitting and receiving data.
host bus adapter (HBA)
Interface card on a Data Mover used to access a storage device, comprising hardware and
loaded microcode.
Name of a computer on a network.
See Hypertext Markup Language.
See Hypertext Transfer Protocol.
Celerra Glossary 6.0
See Hypertext Transfer Protocol Secured.
Central connecting device that joins communication lines together in a star configuration.
See high water mark.
See also metavolume.
Hypertext Markup Language (HTML)
Document format used on the World Wide Web.
Hypertext Transfer Protocol (HTTP)
Communications protocol used to connect to servers on the World Wide Web.
Hypertext Transfer Protocol Secured (HTTPS)
HTTP over SSL. All network traffic between the client and server system is encrypted. In
addition, there is the option to verify server and client identities. Server identities are typically
verified and client identities are not.
Hypertext Transfer Protocol (HTTP)
Communications protocol used to connect to servers on the World Wide Web.
Hypertext Transfer Protocol Secured (HTTPS)
HTTP over SSL. All network traffic between the client and server system is encrypted. In
addition, there is the option to verify server and client identities. Server identities are typically
verified and client identities are not.
Celerra Glossary 6.0
An abbreviation for internationalization. (I + 18 letters + N).
See internationalization.
See Internet Control Message Protocol.
Identity Management for UNIX (IdMU)
Microsoft software that provides a UNIX environment on Windows, specifically UNIX
identity and security services.
idle replication session
Replication session that is configured but is not transferring data from the source site to the
destination site.
See Identity Management for UNIX.
inactive replication session
Replication session that experiences a fatal error. User must stop or delete the replication
session to continue.
include file
Related to Celerra Data Migration Service (CDMS). Lists high-priority files on all drives
from the source file server that should be migrated before all other files. Files are migrated
in an online state. All other files remain in an offline state. Listed entries cannot be a directory.
incremental backup
Term that encompasses both cumulative incremental backups and differential incremental
backups. Any backup that copies only data objects modified since the time of some previous
See also cumulative incremental backup, differential incremental backup, and full backup.
initial copy
Full copy of the source data from the source site to the destination site.
Celerra Glossary 6.0
The process of creating the original baseline copy of a source object for the purpose of
establishing a replication. The baseline copy is then either transported over the network (the
default behavior) or physically by tape or disk from the source site to the destination site.
See also silvering.
“On-disk” data structure that holds information about files in a file system. This information
identifies the file type as being a file that includes Celerra FileMover stub files, a directory,
or a symbolic link.
Communication path between a given Data Mover pair located on the same Celerra cabinet
or different cabinets.
interface (network)
Named logical element mapped to a physical network connection, or port, on a Data Mover.
Each interface assigns an IP address to the port.
internal checkpoint
Read-only, logical point-in-time image of a source object created during replication on the
source and destination sides. Internal checkpoints cannot be managed by users. Replicator
(V2) internal checkpoints are identified by the prefix root_rep_ckpt.
internationalization (I18N)
The process of generalizing software such that it can be made to handle various languages
and locales.
Internet Control Message Protocol (ICMP)
Internet protocol that reports errors and provides control information related to IP-packet
Internet Protocol (IP)
Network layer protocol that is part of the Open Systems Interconnection (OSI) reference
model. IP provides logical addressing and service for end-to-end delivery.
Internet Protocol address (IP address)
Address uniquely identifying a device on any TCP/IP network. Each address consists of
four octets (32 bits), represented as decimal numbers separated by periods. An address is
made up of a network number, an optional subnetwork number, and a host number.
Internet SCSI (iSCSI)
Protocol for sending SCSI packets over TCP/IP networks.
Internet Storage Name Service (iSNS)
Discovery and naming protocol designed to facilitate the automated discovery, management,
and configuration of iSCSI and Fibre Channel Protocol (FCP) devices on a TCP/IP network.
I/O device
Addressable input/output unit, such as a disk device.
Celerra Glossary 6.0
See Internet Protocol.
IP address
See Internet Protocol address.
IP interface
Named logical entity representing a physical device (a port) or a virtual device (a combination
of physical devices) and used to assign an IP address to the device. There may be multiple
IP interfaces associated with a single device.
IP replication service
Service that uses the IP network to transfer the delta sets from the replication SavVol on the
source site to the replication SavVol on the destination site.
See iSCSI qualified name.
See Internet SCSI.
iSCSI host
Computer hosting an iSCSI initiator.
iSCSI initiator
iSCSI endpoint, identified by a unique iSCSI name, which begins an iSCSI session by issuing
a command to the other endpoint (the target).
Celerra iSCSI software feature that processes SCSI commands such as reading from and
writing to storage media.
iSCSI qualified name (IQN)
Naming standard supported by the iSCSI protocol. IQN names are globally unique and in
the form of iqn, followed by a date and a reversed domain name.
iSCSI session
Relationship between two iSCSI endpoints (the initiator and the target) over a group of TCP
iSCSI target
iSCSI endpoint, identified by a unique iSCSI name, which executes commands issued by
the iSCSI initiator.
See Internet Storage Name Service.
Celerra Glossary 6.0
JIS (Japanese Industrial Standards)
Multibyte character encoding system used to represent Japanese. Includes Shift JIS (SJIS)
encoding. The main alternatives to JIS encoding are EUC (used on UNIX systems where the
JIS encodings are incompatible with POSIX standards) and more recently Unicode,
particularly in the form of UTF-8.
jumbo frames
Changes an Ethernet frame’s Maximum Transmission Unit (MTU) from the IEEE 1500 bytes
up to 9000 bytes. Jumbo frames should only be used when the packet to/from any combination
of Ethernet devices can be handled without any Layer 2 fragmentation or reassembly.
Celerra Glossary 6.0
Celerra Glossary 6.0
Authentication, data integrity, and data privacy encryption mechanism used to encode
authentication information. Kerberos coexists with NTLM (Netlogon services) and, using
secret-key cryptography, provides authentication for client/server applications.
Kerberos Key Distribution Center (KDC)
Stores and retrieves information about security principals in the Active Directory database.
Each domain controller in Windows 2000 or later is a Kerberos KDC that acts as a trusted
intermediary between a client and a server.
Software responsible for interacting most directly with the computer’s hardware. The kernel
manages memory, controls user access, maintains file systems, handles interrupts and errors,
performs input and output services, and allocates computer resources.
Kibibytes comes from kilo binary and stands for 1024 in the ISO International System of
Units. Network performance is measured in kibibytes.
kilobit (Kb)
1024 bits.
kilobyte (KB)
1024 bytes.
Celerra Glossary 6.0
Celerra Glossary 6.0
An abbreviation for localization (L+10 letters+N).
See localization.
See local area network.
See link control card.
See Lightweight Directory Access Protocol.
LDAP-based directory
Directory servers that support LDAP, including Active Directory with IdMU, or SFU,
OpenLDAP, or iPlanet (also known as Sun Java System Directory Server and Sun ONE
Directory Server).
Lightweight Directory Access Protocol (LDAP)
Industry-standard information access protocol that runs directly over TCP/IP. It is the
primary access protocol for Active Directory and LDAP-based directory servers. LDAP
version 3 is defined by a set of Proposed Standard documents in Internet Engineering Task
Force (IETF) RFC 2251.
Working data connection between systems on a network. Also, a connection between two
or more ports.
link aggregation
High-availability feature based on the IEEE 802.3ad Link Aggregation Control Protocol
(LACP) standard allowing Ethernet ports with similar characteristics to the same switch to
combine into a single virtual device or link with a single MAC address and potentially
multiple IP addresses.
Celerra Glossary 6.0
link control card (LCC)
Element of a CLARiiON shelf that receives and electrically terminates the incoming Fibre
Channel signal. It passes the signal between shelves in the cabinet and passes the output
signal (through cables) to the next device in the loop.
link-local address
Address that is used for Neighbor Discovery or by applications in an environment where
no routers are present.
load balancing
Process of distributing an I/O workload across all paths.
See also static load balancing and dynamic load balancing.
local area network (LAN)
Minimum of two network nodes communicating through a physical medium over a distance
of less than 3 kilometers.
local backup
Procedure that backs up a file system, or incremental changes to a file system from a Data
Mover to a locally attached TLU.
See also automated backup and restore.
local group
Group that is granted permissions and rights from its own computer to only those resources
on its own computer on which the group resides. Computers must be running Windows
2000 Professional and member servers.
local hosts file
Text file on a Data Mover that contains a list of IP addresses and their corresponding
local mirror
Symmetrix shadow volume that is a complete replica of a production volume within the
same storage unit. If the production volume becomes unavailable, I/O continues to use the
local mirror transparent to the host.
See also R1 volume.
local replication
Replication of a file system on a single Celerra Network Server with the source file system
on one Data Mover and the destination file system on another Data Mover.
A set of user preferences for a particular country or region including language (for example
en-US for American English) and associated settings such as the formatting and parsing of
dates, times, numbers, and currencies, units of measure, sort-order (collation), and translated
names for time zones, languages, and countries.
Celerra Glossary 6.0
localization (L10N)
The process of adapting software for a specific culture or language by adding locale-specific
components and translating text.
locked state
State of a file when its read/write permission is changed to read-only in a file system enabled
for file-level retention. Files committed to the locked (WORM) state cannot be altered or
deleted until their retention date has passed.
logical device
One or more physical devices or partitions managed by the storage controller as a single
logical entity.
See also logical volume.
logical drive
Access point for a logical volume such as C:\ or D:\.
logical unit (LU)
For iSCSI on a Celerra Network Server, a logical unit is an iSCSI software feature that
processes SCSI commands, such as reading from and writing to storage media. From an
iSCSI host perspective, a logical unit appears as a disk device.
logical unit number (LUN)
Identifying number of a SCSI or iSCSI object that processes SCSI commands. The LUN is
the last part of the SCSI address for a SCSI object. The LUN is an ID for the logical unit, but
the term is often used to refer to the logical unit itself.
logical volume
Logical devices aggregated and managed at a higher level by a volume manager.
See also logical device.
loopback replication
Replication of a file system with the source and destination file systems residing on the same
Data Mover.
See logical unit.
See logical unit number.
LUN mask
Set of access permissions that identify which iSCSI initiator can access specific LUNs on a
Celerra Glossary 6.0
MAC address
See media access control.
MAC layer
Media-specific access control protocol within IEEE 802 specifications.
Management Information Base (MIB)
Hierarchical database maintained by an agent that a network management station can query,
using a network management protocol such as the SNMP.
manual local backup
On a Celerra system, a procedure in which an operator enters commands manually or by
using a script. During the backup operation, a single Data Mover or multiple Data Movers
in parallel are backed up fully or incrementally to one or more locally attached tape drives.
Each Data Mover requires its own tape drive, attached to one of the Data Mover’s SCSI or
Fibre Channel ports. Data goes directly to the Celerra system’s attached tape drive, and does
not traverse the network. Also called simple local backup.
maximum concurrent sessions supported
The maximum number of NDMP backup or restore streams that the Data Mover supports.
If the system memory is less than 8 GB, only four concurrent streams are allowed. If the
system memory is more than 8 GB, you can set the concurrent streams to more than four
and up to a maximum of eight.
Maximum Transmission Unit or Maximum Transfer Unit (MTU)
Largest frame size transmitted over the network. Messages longer than the MTU must be
divided into smaller frames. The Layer 3 protocol (including IP, IPX) extracts the MTU from
the Layer 2 protocol (including Ethernet), fragments the messages into that frame size, and
makes them available to the lower layer for transmission.
Megabit. Approximately 1 million bits.
Megabyte. Approximately one million bytes.
Celerra Glossary 6.0
Plural of medium. Variety of physical devices, such as the disk surface on which data is
stored or the physical cable connecting nodes to form a network.
media access control (MAC) address
Data link hardware address every physical device (port) or virtual device needs to connect
to a network segment. These addresses are used by network devices to locate the logical
member server
Computer joined to a domain, but not a domain controller of the domain. Member servers
participate in a domain, but do not perform domain user-account authentication. For a
member server, permissions can be set on resources so that only authorized users can connect
to the server and use its resources. Resource permissions can be granted for domain global
groups and users as well as local groups and users.
Data that contains structural information, such as access methods, about itself.
On a Celerra system, a concatenation of volumes, which can consist of disk, slice, or stripe
volumes. Also called a hypervolume or hyper. Every file system must be created on top of
a unique metavolume.
See also disk volume, slice volume, stripe volume, and volume.
See Migration File System.
See Management Information Base.
Microsoft Distributed File System (DFS)
Windows operating systems service that consists of software residing on network servers
and clients that transparently links shared folders located on different file servers into a
single namespace.
Microsoft Management Console (MMC)
Extensible common presentation service for management applications included in the
Windows operating system.
See also MMC snap-in.
Microsoft Windows Services for UNIX (SFU)
Microsoft software that provides a UNIX environment on Windows.
Migration File System (MGFS)
EMC file system type used to perform data migration from either CIFS or NFS to the Celerra
Network Server.
mirrored pair
Logical volume with all data recorded twice, once on each of two different physical devices.
Celerra Glossary 6.0
Method by which the storage system maintains two identical copies of a designated volume
on separate disks.
MirrorView Synchronous (MirrorView/S)
Software application that synchronously maintains copies of production images (source
LUNs) at a separate location to provide disaster recovery capability. The copied images are
continuously updated to be consistent with the source, and provide the ability for a standby
Celerra to take over for a failed Celerra in the event of a disaster on the production site.
Synchronous remote mirrors (source and destination LUNs) remain in synchronization with
each other for every I/O. MirrorView/S requires CLARiiON backend storage.
See Microsoft Management Console.
MMC snap-in
Management tool an administrator can add to the interface of a Microsoft Management
Console (MMC).
See also Microsoft Management Console.
Process of attaching a subdirectory of a remote file system to a mount point on the local
mount point
Local subdirectory to which a mount operation attaches a subdirectory of a remote file
See Multi-Path File System.
MPFS session
Connection between an MPFS client and a Celerra Network Server.
MPFS share
Shared resource designated for multiplexed communications by using the MPFS file system.
See Multiprotocol Support Layer.
See Maximum Transmission Unit or Maximum Transfer Unit.
multibyte support
Generic term for encoding schemes for characters that may require more than one byte.
Communication between one sender and multiple receivers. Multicast messages are sent to
a defined subset of network addresses.
Multi-Path File System (MPFS)
Celerra Network Server feature that allows heterogeneous servers with MPFS software to
concurrently access, directly over Fibre Channel or iSCSI channels, shared data stored on a
EMC Symmetrix® or CLARiiON® storage array. MPFS adds a lightweight protocol called
File Mapping Protocol (FMP) that controls metadata operations.
Multiprotocol Support Layer (MSL)
On a Celerra system, the data access in real time (DART) operating system layer that allows
both NFS and CIFS protocols to access a file system.
Celerra Glossary 6.0
native mode
Normal operating mode of a computer, as opposed to emulation mode.
Enables you to discover, monitor, provision, and report on EMC CLARiiON storage systems
from your web browser.
See Network Block Service.
See Network Data Management Protocol.
See NDMP Backup-to-Disk.
NDMP Backup-to-Disk (NDMP2D)
Software-based virtual tape library configured on a Data Mover that emulates a real TLU,
and allows NDMP backup-to-disk functionality. This feature is sometimes referred to as a
virtual tape library unit (VTLU). However, it does not provide true VTLU functionality as
found in EMC Disk Library and similar storage products.
NDMP client
Application that controls the NDMP session. The NDMP client runs an NDMP-compliant
backup application, such as EMC NetWorker®.
NDMP host
Host system (Data Mover) that executes the NDMP server application. Data is backed up
from the NDMP host to either a local tape drive or to a backup device on a remote NDMP
NDMP server
NDMP process that runs on an NDMP host, which is a Data Mover in a Celerra Network
Server environment.
Celerra Glossary 6.0
NDMP Volume Backup (NVB)
EMC-specific type of NDMP backup mechanism that backs up data blocks at a volume level,
rather than at a file level. NVB reads a set of disk data blocks in an efficient manner compared
to the method used for traditional, file-based backups. NVB works only with EMC-qualified
vendor backup software. NVB is commonly known as Volume Based Backup (VBB).
See Network Data Management Service.
Neighbor Discovery
IPv6 protocol used for address resolution, prefix detection, default router detection and
settings, and redirect functions. It uses link-local addresses for communication.
nested export
Export of a component file system. The export has its own specified access controls.
nested mount file system (NMFS)
File system that contains the nested mount root file system and component file systems.
nested mount file system root
File system on which the component file systems are mounted read-only, except for mount
points of the component file systems.
See network basic input/output system.
NetBIOS alias
Alternative NetBIOS name. NetBIOS aliases provide multiple, alternate identities for a given
NetBIOS name
Name recognized by WINS, which maps the name to an IP address.
Group of computers on a network administered by using a single name. Netgroups can be
defined by using a local text file that provides the list of hosts in a netgroup, or by using
NIS or an LDAP-based directory server.
Combination of devices, cabling, and software that makes up a communication infrastructure.
network-attached storage (NAS)
Specialized file server that connects to the network. A NAS device, such as a Celerra Network
Server, contains a specialized operating system and a file system, and processes only I/O
requests by supporting popular file sharing protocols such as NFS and CIFS.
network backup
See remote backup.
network basic input/output system (NetBIOS)
Network programming interface and protocol developed for IBM personal computers.
Celerra Glossary 6.0
Network Block Service (NBS)
Proprietary client/server protocol of the Celerra Network Server that provides a Celerra
block device (for example, iSCSI device) management functionality over a TCP/IP connection.
Supported block device management functions include snapshots and remote replication.
For the NS series, NBS provides Control Station access to local network disks.
Network Data Management Protocol (NDMP)
Open standard network protocol designed for enterprise-wide backup and recovery of
heterogeneous network-attached storage.
Network Data Management Service (NDMS)
Network communication service that uses the Network Data Management Protocol (NDMP)
and contains its own backup and retrieval utilities.
network element
SNMP-managed devices such as hosts, gateways, and terminal servers on a network.
network file system (NFS)
Network file system (NFS) is a network file system protocol that allows a user on a client
computer to access files over a network as easily as if the network devices were attached to
its local disks.
Network Information Service (NIS)
Distributed data lookup service that shares user and system information across a network,
including usernames, passwords, home directories, groups, hostnames, IP addresses, and
netgroup definitions.
network interface card (NIC)
Circuit board that provides network communication capabilities to and from a computer
network lock manager (NLM)
Service that allows clients to lock files or byte ranges.
network management station (NMS)
Systems that execute management applications, such as SNMP commands to monitor and
control network elements.
network node
Network connection point.
network portal
Component that listens for and is capable of accepting iSCSI connections within a given
iSCSI session. A network portal for an iSCSI initiator is identified by its IP address. A network
portal for an iSCSI target is identified by its IP address, listening port, and group tag.
network status monitor (NSM)
Protocol that allows NFS clients and servers to monitor each other’s status and be aware of
Network Time Protocol (NTP)
Protocol used to synchronize the realtime clock in a computer with a network time source.
See network file system.
See network interface card.
See Network Information Services.
See network lock manager.
See nested mount file system.
See network management station.
not locked state
Initial state of a file when it is created. A file that is not locked is treated in the same manner
as any file in a file system not enabled for file-level retention (FLR). This means it can be
renamed, modified, and deleted until the time that the file is locked.
Actions the Control Station takes in response to particular events. Some possible actions
include sending an email message or an SNMP trap. There are two types of notifications:
event notifications, which are notifications based on predefined system events such as a
temperature being too high, and resource notifications, which are notifications based on
user-specified resource usage limits or thresholds.
See network status monitor.
NT file system (NTFS)
NTFS is the standard file system of Windows NT, including its later versions. NTFS
supersedes the FAT file system as the preferred file system for Microsoft Windows. NTFS
has several improvements over FAT such as improved support for metadata and the use of
advanced data structures to improve performance, reliability, and disk space utilization,
plus additional extensions such as security access control lists (ACL) and file system
See Network Time Protocol.
Celerra Glossary 6.0
Customized software used to support mapping requirements in a multiprotocol environment.
See NDMP Volume Backup.
Celerra Glossary 6.0
Nodes on the same broadcast domain.
Open-source implementation of an LDAP-based directory service.
Open Systems Interconnection (OSI)
International Standards Organization (ISO) standard for worldwide communications that
defines a framework for implementing protocols in seven layers.
organizational unit (OU)
Active Directory container object that is used within domains. An organizational unit (OU)
is a logical container where users, groups, computers, and other organizational units are
placed. The OU can contain objects only from its parent domain. An OU is the smallest scope
to which a Group Policy Object can be linked, or over which administrative authority can
be delegated.
orphan file
File that exists on secondary storage, but is no longer referenced by a stub file on the Celerra
Network Server. An orphan file is kept intact on secondary storage; it can be managed by
the system administrator.
See Open Systems Interconnection.
Celerra Glossary 6.0
Celerra Glossary 6.0
In communications, a fixed block of data transmitted as a single entity. In local area networks
(LANs), the terms frame and packet are used synonymously.
See also frame.
Archiving method option that instructs the Celerra Network Server to read the requested
data from secondary storage. The data is returned to the client, but is not recalled to primary
storage; thus the stub file remains intact.
Route to a file or directory on a disk.
On a Celerra system, when a SnapSure checkpoint is created, the system pauses the file
system before creating the bitmap. The system stops responding to network requests (but
does not drop the connection), allows requests in process to complete, and then internally
locks the file system. This puts the file system in a consistent state for the creation of the
checkpoint bitmap.
See Portable Archive Interchange.
See Persistent Block Reservation.
See Peripheral Component Interconnect.
See preconfigured single enclosure.
See primary domain controller.
Celerra Glossary 6.0
See Protocol Data Unit.
Peripheral Component Interconnect (PCI)
Peripheral bus used to provide a high-speed data path between the CPU and peripheral
Persistent Block Reservation (PBR)
Technique of reserving an adequate number of blocks in a file system to support creation
of a logical unit of a specified size. The blocks are reserved for the logical unit whether or
not in use.
Means of providing an identity for a Data Mover as either a server or a client through a
private key and associated public key certificate. Each persona can maintain up to two sets
of keys (current and next), to allow for the generation of new keys and certificates prior to
the expiration of the current certificate.
See production file system.
PFS application
Business application that accesses a PFS and performs transactions, such as read, write, or
delete on the PFS blocks.
See also production file system.
physical volume
Disk device on the backend storage system. A Celerra system addresses the physical volumes
of a storage system through logical disk volumes.
See also volume.
See public key infrastructure.
playback service
Process of reading the delta sets from the destination SavVol and updating the destination
file system.
See production logical unit.
The parallel NFS (pNFS) is part of NFS version 4.1 that allows the clients to access storage
device directly and in parallel.
Set of rules used to guide Celerra FileMover software about when to backup, archive, or
migrate files from one data store to another.
Celerra Glossary 6.0
policy and archiving software
Policy and software used to archive data from the Celerra Network Server to secondary
storage according to customer-defined policies and schedules.
policy engine
External server on which the policy and archiving software runs.
pop-up messages
Feature that warns or informs Microsoft Windows clients (connected to a specific machine
name) when certain system events occur. Pop-up messages can be customized to provide
specific instructions or contact information.
Physical connection point to a network or a number used at the transport layer to track
host-to-host virtual circuits.
Port Range
The range of port numbers that is defined by a user to listen for NDMP data connections.
It is recommended to use dynamic or private ports (49152-65535) of IANA to set the NDMP
port range.
Port Width
The number of ports that are present in a port range. The required minimum port width is
32. However, it is recommended that the port width should be at least 100.
Portable Archive Interchange (PAX)
Celerra Network Server archive protocol that works with standard UNIX tape formats and
provides file-level backup and recovery operations.
portal group
Collection of network portals for a given iSCSI target.
RPC service that assigns port numbers to applications. On a Celerra system, the portmapper
allows clients access to the services registered on the Data Mover.
See power on self-test.
power on self-test (POST)
Series of built-in diagnostics performed by the BIOS in a personal computer when it is first
EMC host-resident software that integrates multiple path I/O capabilities, automatic load
balancing, and path failover functions into one comprehensive package for use on open
server platforms connected to Symmetrix or CLARiiON enterprise storage systems.
preconfigured single enclosure (PCSE)
Celerra system preconfigured at the factory with a Celerra Network Server and Symmetrix
array in one cabinet.
primary Control Station
Provides utilities for managing, configuring, and monitoring of the Data Movers in the
Celerra Network Server. Many Celerra Network Servers support configurations with dual,
redundant Control Stations, a primary and secondary Control Station. Under normal
circumstances, after the primary Control Station fails over, you can continue to use the
secondary Control Station as the primary.
See also Control Station, secondary Control Station, and standby device.
primary domain controller (PDC)
Windows NT service that manages security for its local domain.
See also BDC.
primary group
Group identified on NFS systems by the group identifier (GID) in the fourth column of the
password file. This is set through the Windows User Manager in a Microsoft Windows
primary storage
Celerra Network Server that provides clients access to normal files and archived files through
the stub files that represent them. The Celerra Network Server contains all the stub files.
primary Usermapper service
Instance of the Usermapper service that assigns user IDs (UIDs) and GIDs to Windows users
and groups by asking the Celerra Network Server for access to system objects.
Unique name to which the Kerberos Key Distribution Center (KDC) can assign tickets. A
principal can be a user, service, or server.
production file system (PFS)
Production file system on a Celerra Network Server. A PFS is built on Symmetrix volumes
or CLARiiON LUNs and mounted on a Data Mover in the Celerra Network Server.
production logical unit (PLU)
iSCSI LUN that serves as a primary storage device. A PLU can be configured as a disk device
through an iSCSI initiator.
To mount a snapshot to an iSCSI LUN, so it can be configured as a disk device through an
iSCSI initiator.
Standard defined between the client and the user that determines how information is
transferred and interpreted over a network.
Protocol Data Unit (PDU)
iSCSI term for a fixed block of data transmitted as a single entity. A PDU is an iSCSI packet.
Celerra Glossary 6.0
public key infrastructure (PKI)
Means of managing private keys and associated public key certificates for use in public key
cryptography. It is a framework which allows the creation of a certificate which is used by
Celerra Glossary 6.0
qualified name
Name of an iSCSI target or initiator in IQN or EUI format.
Limit on the amount of allocated disk space and the number of files (inodes) that a user or
group of users can create in a production file system. Quotas control the amount of disk
space or the number of files that a user or group of users can consume or both.
quota policy
Parameter you set to tell the Celerra Network Server to calculate disk usage either by blocks
or by file size. (Default is by blocks.)
quota tree
Directory or subdirectory to which tree quotas are applied.
Celerra Glossary 6.0
Celerra Glossary 6.0
R1 volume
SRDF term denoting the source (primary) Symmetrix volume.
See also local mirror.
R2 volume
SRDF term denoting the destination (secondary) Symmetrix volume.
See also remote mirror.
See redundant array of independent disks.
RAID method that provides data integrity by mirroring (copying) data onto another disk
in the LUN. This RAID type provides the greatest data integrity at the greatest cost in disk
RAID 1/0
RAID method that mirrors and stripes, with data being written to two disks simultaneously.
Data transfer rates are higher than with RAID 5, but RAID 1/0 uses more disk space for
Data is striped across disks in large stripes. Parity information is stored so data can be
reconstructed if needed. One disk can fail without data loss. Performance is good for reads,
but slow for writes.
Data and parity are striped on a block level across multiple disks. Two sets of parity data
are maintained. RAID 6 provides an extremely high fault tolerance, and can sustain two
simultaneous drive failures without data loss.
RAID group
CLARiiON storage-system term for a NS600 disk group.
Celerra Glossary 6.0
EMC proprietary variant of RAID 5.
read hit
Data requested by a read operation in global memory.
read miss
Data requested by a read operation not in global memory.
read-only checkpoint
Read-only, point-in-time, logical image of a PFS.
See also production file system.
In a networked environment, a set of security principals (users, service, computers) subject
to Kerberos authentication, and managed by the same Kerberos authority.
reason code
On a Celerra system, a number representing the state of a Data Mover.
recall policy
Attribute that is set per individual file and is in the stub file when a file is archived to
secondary storage. The Celerra Network Server uses the recall policy to determine the
amount of data that is recalled to primary storage to satisfy the client read request.
recovery point objective (RPO)
Describes the acceptable amount of data loss, measured in units of time, for example, 12
minutes, 2 hours, or 1 day. This represents a target that is derived from conditions specified
in an SLA, RTO, and relevent analyses. The RPO in conjunction with the recovery time
objective (RTO) is the basis on which data protection strategy is developed.
recovery time objective (RTO)
How long a business process can be down before consequences are unacceptable. This
represents a target that is derived from conditions specified in an SLA and business impact
Redundant Array of Independent Disks (RAID)
Method for storing information where the data is stored on multiple disk drives to increase
performance and storage capacities and to provide redundancy and fault tolerance.
redundant components
Backup arrays, drives, disks, or power supplies that duplicate functions performed elsewhere.
Process to undo the effect of Celerra deduplication on a file. If the file was compressed, it
will be decompressed. If there are multiple instances of the file data, then a copy of the file
data is made so that blocks are not shared between instances of the file. This process consumes
additional space in the file system. Therefore, there must be sufficient free space in the file
system to hold an additional copy of the original file for this process to complete.
Celerra Glossary 6.0
regular iSCSI LUN
iSCSI LUN that uses Persistent Block Reservation (PBR) to ensure that the file system has
sufficient space for all data that might be written to the LUN.
remote backup
Remotely initiated procedure that backs up data to a TLU which can be attached to a target
server different from the source Data Mover. The configuration determines whether data
traverses the network.
See also automated backup and restore and three-way backup.
remote mirror
For SRDF, a remote mirror is a Symmetrix shadow volume physically located in a remote
Symmetrix system. Using the EMC SRDF technology, the remote system is joined to a local
system with a local mirror. If the local mirror becomes unavailable, the remote mirror is
accessible. For MirrorView/S, a remote mirror is a LUN mirrored on a different CLARiiON
storage system. Each remote mirror contains a particular source LUN (primary image) and
its equivalent destination LUN (secondary image). If the source site system fails, the
destination LUN in the mirror can be promoted to take over, thus allowing access to data
at a remote location.
See also R2 volume.
remote procedure call (RPC)
Programming interface that allows one program to utilize the services of another program
in a remote machine.
remote replication
Replication of a file system from one Celerra Network Server to another. The source file
system resides on a different Celerra system from the destination file system.
remote three-way backup
See heterogeneous three-way backup.
Service that produces a read-only, point-in-time copy of a source file system. The service
periodically updates the copy, making it consistent with the source file system.
replication reversal
Process of reversing the direction of replication. The source file system becomes read-only
and the destination file system becomes read/write.
replication service
Service that copies modified blocks from a source file system to a replication SavVol prior
to transferring the data to the destination file system.
Replicator ConfigVol
Internal information store for replication. Provides a storage vehicle for tracking changes
in the source file system.
Replicator failover
Process that changes the destination file system from read-only to read/write and stops the
transmission of replicated data. The source file system, if available, becomes read-only.
Replicator SavVol
Celerra volume, required by replication, used to store modified data blocks from the source
file system.
Request for Comment (RFC)
Name given to Internet standards.
retention date
Date until which a locked file in an FLR-enabled file system will be protected. Users and
applications manage a file's retention date by using NFS or CIFS to set the file's last access
time to a future date and time. The retention timestamp is compared to the file system's FLR
clock to determine whether a file's retention date has passed.
See Request for Comment.
See routing information protocol.
Device that transfers information between networks and determines the most efficient route
for it to follow.
routing information protocol (RIP)
Routing protocol optimized for creating routes within one organization (interior gateway
protocol). RIP is a distance vector protocol that uses hop count (max 15) as the metric. RIP-1
does not send the mask in updates. RIP-2 sends the mask in updates.
See remote procedure call.
See recovery point objective.
See recovery time objective.
Celerra Glossary 6.0
See Security Access Manager or Security Accounts Manager.
See storage area network.
Standard Celerra metavolume to which SnapSure writes checkpoint data. This volume can
be smaller than the production file system upon which the checkpoint is based.
SavVol extend
Process of enlarging the SavVol space to ensure that it does not become full and inactivate
one or more checkpoints. By default, and as system resources permit, SnapSure automatically
extends the SavVol each time the HWM is reached.
See also high water mark.
Process of reading, checking error-correction bits, and writing corrected data back to the
See small computer system interface.
SCSI adapter
Circuit board in a storage system that provides the physical interface between the disk
director and the disk devices.
SCSI bus
Parallel bus that carries data and control signals from SCSI devices to a SCSI controller.
See SCSI common access method.
SCSI common access method (SCSI CAM)
American National Standards Institute (ANSI) standard interface that provides a common
language between device drivers and SCSI adapters.
Celerra Glossary 6.0
See security descriptor.
secondary Control Station
If the primary Control Station goes offline, the secondary Control Station, if properly
configured, automatically takes over all primary Control Station functions and executes any
of the Celerra Network Server commands you enter. After the primary Control Station is
repaired or replaced and the Controls Stations are rebooted, the first Control Station to start
is restored as the primary.
See also Control Station, primary Control Station, and standby device.
See secure mapping.
secondary storage
Storage device that contains original files associated with stub files on the primary storage.
This device must be either a CIFS, HTTP, HTTPS, or NFS server. The Celerra Network Server
can also be secondary storage.
secondary Usermapper service
In a multi-Celerra environment, an instance of the Usermapper service that forwards requests
for user mappings to the primary Usermapper service and returns those mappings to the
Data Movers in addition to storing the mappings it processes.
secure mapping (secmap)
Cache that contains all mappings between SIDs and UID or GIDs used by a Data Mover or
Virtual Data Mover (VDM).
secure shell protocol
Enables you to execute Celerra CLI commands through a secure shell directly onto the
Control Station. The SSH protocol encrypts the data sent between your computer and the
Control Station. Interactive features are not supported by the CLI commands option.
Secure Sockets Layer (SSL)
Security protocol that provides encryption and authentication. It encrypts data and provides
message and server authentication. It also supports client authentication if required by the
Security Access Manager or Security Accounts Manager (SAM)
Microsoft Windows service that authenticates users to use resources on the network. The
SAM database is the location for all security and user account information for a Windows
NT domain.
security descriptor (SD)
In a Microsoft Windows environment, information associated with a file that includes the
owner and the group SID for the file’s access control list (ACL).
security identifier (SID)
Unique identifier that defines a user or group in a Microsoft Windows environment. Each
user or group has its own SID.
Celerra Glossary 6.0
security mode
Setting that specifies how a Data Mover performs authentication for CIFS users. The security
mode is set for each Data Mover not for a file system.
Device that handles requests made by clients connected through a network.
Server Message Block (SMB)
Underlying protocol used by the CIFS protocol enhanced for use on the Internet to request
file, print, and communication services from a server over the network. The CIFS protocol
uses SMB to provide secure file access and transfer to many types of hosts such as LANs,
intranets, and the Internet.
service level agreement (SLA)
Contract or agreement that formally defines the level of expected availability, serviceability,
performance, operation, or other attributes of service and even penalties in the case of
violation of the SLA. An SLA may include acceptable downtime or disaster recovery time.
In theory an SLA is a formal agreement, but in practice it is often informal in which case it
may be called a service level expectation (SLE).
service processor (SP)
Service processor on a Symmetrix storage system. The device running the Symmetrix
monitoring software.
See Microsoft Windows Services for UNIX.
shadow copy
Point-in-time copy created through Microsoft's Volume Shadow Copy Service.
Shadow Copy for Shared Folders (SCSF)
Microsoft Windows feature that provides Windows XP and Windows Server 2003 clients
direct access to SnapSure point-in-time images of their files and folders for the purpose of
recovering point-in-time data.
File system, directory, or service that has been made available to CIFS users on the network.
Also, the process of making a file system, directory, or service available to CIFS users on
the network.
share name
Name given to a file system, or resource on a file system available from a particular CIFS
server to CIFS users. There may be multiple shares with the same name, shared from different
CIFS servers.
On a CLARiiON system, the common functional components in either a disk-array enclosure
(DAE) or disk-array processor enclosure (DPE).
See security identifier.
See initialization.
Simple Mail Transfer Protocol (SMTP)
Standard email protocol on the Internet.
Simple Network Management Protocol (SNMP)
Method used to communicate management information between the network management
stations and the agents in the network elements.
Simple Network Time Protocol (SNTP)
Adaptation of the Network Time Protocol (NTP) used to synchronize computer clocks in
the Internet.
See also NTP.
single enclosure
skew (time)
Time difference between a Celerra Network Server and its network clients.
See service level agreement.
Process of gradually correcting the local system time.
slice volume
On a Celerra system, a logical piece or specified area of a volume used to create smaller,
more manageable units of storage.
See also disk volume, metavolume, stripe volume, and volume.
See snapshot logical unit.
small computer system interface (SCSI)
Standard set of protocols for host computers communicating with attached peripherals.
See Server Message Block.
See Simple Mail Transfer Protocol.
Generic term for a point-in-time copy of data.
Celerra Glossary 6.0
snapshot logical unit (SLU)
Snapshot promoted to logical unit status and configurable as a disk device through an iSCSI
Snapshot Virtual File System (SVFS)
File system that allows an NFS or a CIFS client read-only access to online snapshots of a file
system directory by accessing a virtual .ckpt directory entry. SVFS and CVFS are synonymous
On a Celerra system, a feature providing read-only point-in-time copies, also known as
checkpoints, of a file system.
SnapSure SavVol
Celerra volume to which SnapSure copies original point-in-time data blocks from the
production file system (PFS) before the blocks are altered by a transaction. SnapSure uses
the contents of the SavVol and the unchanged PFS blocks to maintain a checkpoint of the
See Simple Network Management Protocol.
SNMP agent
Software module in a managed device, such as a Celerra Network Server or Symmetrix
storage system, that maintains local management information and delivers that information
to a manager by using SNMP.
SNMP community
Name for the SNMP transaction with a remote system. This is used as a password to control
access to the SNMP MIB.
SNMP trap
Asynchronous message sent from an SNMP agent to an SNMP management program. Traps
are typically used to report errors. A Celerra Network Server can be configured to send
SNMP traps when specified events occur.
See also event notification.
See Simple Network Time Protocol.
soft quota
Configurable file system usage limit that, when reached, can cause the system to generate
an event, and send a warning message to Windows clients. The soft quota limit serves as a
grace period providing reaction time so that reaching the hard quota can be avoided.
See also quota and hard quota.
software virtual tape library (SVTL)
source Celerra
Term for the local (primary) Celerra Network Server. A source Celerra is typically the
“production” side of a disaster recovery SRDF/S or MirrorView/S configuration.
source object
The production data being copied. Also known as the production file system, production
LUN, and primary file system. Celerra Replicator (V2) source objects are file systems, iSCSI
LUNS, and Virtual Data Movers (VDM).
See storage processor and service processor.
See storage processor A.
spare disk device
Disk device that can take over for a failed disk device.
See storage processor B.
See storage processor enclosure.
See standby power supply.
See Symmetrix Remote Data Facility.
SRDF channel
Method used to move information between the Control Stations of Celerra Network Servers
joined in an SRDF configuration.
SRDF/Asynchronous (SRDF/A)
SRDF extended-distance replication facility providing a restartable, point-in-time remote
replica that lags not far behind the source. Using SRDF/A with Celerra provides dependent
write consistency for host writes from a source Celerra/Symmetrix DMX system pair to a
destination Celerra/Symmetrix DMX system pair through predetermined time cycles (delta
SRDF/Synchronous (SRDF/S)
SRDF complete disaster recovery configuration option that provides synchronized, real-time
mirroring of file system data between the source Symmetrix system and one or more remote
Symmetrix systems at a limited distance (up to 200 kilometers). SRDF/S can include EMC
TimeFinder® /FS NearCopy in the configuration (active/passive; active/active’).
See secure shell protocol.
Celerra Glossary 6.0
See Secure Sockets Layer.
See storage service provider.
stand-alone CIFS server
Type of CIFS server that uses local user accounts on the Data Mover and therefore does not
require any Windows domain infrastructure. When users log in to a stand-alone server,
NTLM is used to authenticate users against the local accounts database.
standard volume (STD)
Active application volume containing a production file system (production data and
programs). An STD volume is a local volume on a Symmetrix system upon which the Celerra
Network Server builds the production file system.
See also business continuance volume.
standby device
Device held in reserve against a failure of its active partner. When the active device fails,
the standby device takes over.
standby power supply (SPS)
Battery system used to provide power to a CLARiiON storage system during a power failure.
static load balancing
Assigns different devices to different physical paths in distributing an I/O workload, so that
all paths are used for one or more devices.
See also load balancing and dynamic load balancing.
See standard volume.
storage area network (SAN)
Network of data storage disks. In large enterprises, a SAN connects multiple servers to a
centralized pool of disk storage.
See also network-attached storage (NAS).
storage device
Physical device that can attach to a SCSI device, which connects to the SCSI bus.
storage pool
Automatic Volume Management (AVM), a Celerra feature, organizes available disk volumes
into groupings called storage pools. Storage pools are used to allocate available storage to
Celerra file systems. Storage pools can be created automatically by AVM or manually by
the user.
storage processor (SP)
Storage processor on a CLARiiON storage system. On a CLARiiON storage system, a circuit
board with memory modules and control logic that manages the storage system I/O between
the host’s Fibre Channel adapter and the disk modules.
Storage processor A (SP A)
Generic term for the first storage processor in a CLARiiON storage system.
Storage processor B (SP B)
Generic term for the second storage processor in a CLARiiON storage system.
storage processor enclosure (SPE)
Shelf in a CLARiiON storage system that includes an enclosure, storage processors (SPs),
Fibre Channel link control cards (LCCs), two power supplies, and fan packs.
storage profile
Predefined set of parameters used to configure a disk volume. Every disk volume on a
Celerra Network Server is associated with a single storage profile. The parameters specify
the RAID type of the disk volume, the storage processor associated with the disk group,
and other information.
storage service provider (SSP)
Third-party provider that manages the storage facilities for an enterprise.
storage system
Array of physical disk devices and their supporting processors, power supplies, and cables.
stripe size
Number of blocks in one stripe of a stripe volume.
stripe volume
Arrangement of volumes that appear as a single volume. Allows for stripe units that cut
across the volume and are addressed in an interlaced manner. Stripe volumes make load
balancing possible.
See also disk volume, metavolume, and slice volume.
stub file
File that replaces the original file on the Celerra Network Server when the file is archived
to secondary storage. The stub file contains all the metadata associated with the archived
file and the information required by the Celerra Network Server to allow it to access the
archived data on secondary storage when required.
Any network that is part of a larger IP network as identified by the IP address and subnet
subnet mask
32-bit address mask used in IP to identify the bits of an IP address used for the subnet
Celerra Glossary 6.0
Sun Java System Directory Server
Also known as Sun ONE Directory Server and iPlanet. A distributed directory service
accessible by using LDAP.
See Snapshot Virtual File System.
See software virtual tape library.
Network device that selects a path or circuit for sending data between destinations.
switch fabric
Combination of interconnected Fibre Channel switches used throughout a campus or large
geographical area, which collectively provide a routing infrastructure.
Replication operation that snychronizes the destination object with the source, stops the
replication with no data loss, and then mounts the destination object read/write and the
source object read-only.
symbolic link
File that points to another file or directory.
Symmetrix Integrated Cached Disk Array (Symmetrix ICDA)
Storage array that provides centralized, sharable enterprise storage. It helps create an
information infrastructure capable of managing large, complex ultra-dynamic storage area
network (SAN) environments by consolidating storage from multiple heterogeneous hosts
onto a single system.
Symmetrix Remote Data Facility (SRDF)
EMC technology that allows two or more Symmetrix systems to maintain a remote mirror
of data in more than one location. The systems can be located within the same facility, in a
campus, or hundreds of miles apart using fibre or dedicated high-speed circuits. The SRDF
family of replication software offers various levels of high-availability configurations, such
as SRDF/Synchronous (SRDF/S) and SRDF/Asynchronous (SRDF/A).
system configured concurrent streams
The number of NDMP backup or restore streams that can run concurrently. This number
can be modified using the server_param command.
system-defined storage pool
Predefined AVM storage pools that are set up to help you easily manage both storage volume
structures and file system provisioning by using AVM.
Celerra Glossary 6.0
See frame tagging.
tape library unit (TLU)
Physical device that contains and manages sets of tape drives and cartridges.
Backup format in PAX that traverses a file tree in depth-first order.
target Celerra
SRDF term for the remote (secondary) Celerra Network Server. The target Celerra is typically
the "standby" side of a disaster recovery configuration.
See terabyte.
See Transmission Control Protocol.
TCP Offload Engine (TOE)
TOE network interface card offloads TCP protocol stack processing from the host and helps
improve network performance and reduce CPU utilization.
Internet standard protocol for remote terminal connection, which allows a user at one site
to interact with a remote device or system that expects terminal-mode traffic.
Predefined set of parameters used to configure all new disk devices that are added to the
storage system.
terabyte (TB)
2 to the 40th power (1,099,511,627,776) bytes, or approximately 1 trillion bytes.
See Trivial File Transfer Protocol.
Celerra Glossary 6.0
Sequential flow of control in a computer program. A thread consists of address space, a
stack, local variables, and global variables.
three-way backup
NDMP backup that directs data from one Data Mover through a network connection to a
remote Data Mover to its attached tape library backup device.
See also heterogeneous three-way backup and remote backup.
throttle schedule
See bandwidth schedule.
In computers, a measurement of the work that can be processed within a set time period.
In networking, a measurement of the amount of data that can be successfully transferred
within a set time period.
See Transfer Identifier.
Business continuance configuration allowing customers to use Symmetrix business
continuance volumes (BCVs) to provide a local or remote point-in-time copy of a Celerra
file system.
time offset
Difference between local system time and time retrieved from a time server.
Time interval at which the system takes some predetermined action.
time out of sync
Maximum amount of time in minutes (1–1440), or hours that the source object and the
destination object in a replication session can be out of synchronization before an update is
time to live (TTL) time stamp
TTL time stamp is used to maintain the consistency of the credential. In case the TTL expires,
the credential is rebuilt to take into account any modification that might have occurred.
See Transport Layer Security.
See tape library unit.
See TCP Offload Engine.
Celerra Glossary 6.0
Transfer Identifier (TID)
Randomly chosen identifiers used by TFTP and passed to the Datagram layer to be used as
ports during the connection. TIDs must be between 0 and 65,535.
Transmission Control Protocol (TCP)
Connection-oriented transport protocol that provides reliable data delivery.
Transport Layer Security (TLS)
Successor protocol to SSL for general communication authentication and encryption over
TCP/IP networks. TLS version 1 is nearly identical with SSL version 3.
Asynchronous message sent from an SNMP agent to an SNMP management program. Traps
are typically used to report errors.
tree quota
Feature that lets you specify soft and hard quota limits on a directory tree. The usage is
computed for all files created in the tree hierarchy.
Trivial File Transfer Protocol (TFTP)
Simple, UDP-based protocol to read and write files. TFTP can be used to boot remote clients
from a network server, but does not authenticate users or provide access control.
Set of physical network devices bundled together for high availability. Ethernet channels
and link aggregations are trunks.
TTL time stamp
See time to live (TTL) time stamp.
two-way back-up
NDMP backup that directs data from a Data Mover (NDMP server) to the tape library device
attached to the Data Mover.
Celerra Glossary 6.0
Unit of measurement for rackmount equipment. One U is 1.75 inches (4.44 centimeters).
UCS-2 (Universal Character Set-2)
An obsolete character encoding which is a predecessor to UTF-16.
See User Datagram Protocol.
See UNIX file system.
See Ultra fast-wide differential SCSI.
See User ID.
Ultra fast-wide differential SCSI (UFWD SCSI)
High-speed channel connection between Data Movers and the storage system.
See also Fibre Channel.
See universal naming convention.
Family of universal character encoding standards used for representation of text for computer
Unicode Consortium
Organization responsible for defining the behavior of and relationships among Unicode
characters and for providing technical information to implementors (www.unicode.org).
Unicode or UCS Transformation Format-8 (UTF-8)
Multibyte encoding form, UTF-8 uses an algorithmic mapping scheme to convert every
Unicode value to a unique 1- to 4-byte sequence with no embedded null characters.
Celerra Glossary 6.0
unified storage
Celerra network server that is connected to a captive storage array that is not shared with
any other Celerra network servers and is not capable of connecting to multiple storage
uniform resource locator (URL)
Address for a page in the World Wide Web. A URL usually consists of an access protocol,
a domain name, and optionally a path to a file or other resource.
Universal Extended File System (UxFS)
High-performance, Celerra Network Server default file system, based on traditional Berkeley
UFS, enhanced with 64-bit support, metadata logging for high availability, and several
performance enhancements.
universal naming convention (UNC)
Standard for identifying servers, printers, and other resources in a network. Originated in
the UNIX community.
UNIX file system (UFS)
Standard UNIX file system.
See uniform resource locator.
User Datagram Protocol (UDP)
Connectionless transport protocol in the TCP/IP stack that allows datagrams to be exchanged
without acknowledgements or a delivery guarantee.
user-defined storage pools
User-created storage pools containing volumes that are manually added. User-defined
storage pools provide an appropriate option for users who want control over their storage
volume structures while still using the automated file system provisioning functionality of
AVM to provision file systems from the user-defined storage pools.
user file
Refers to the passwd file that resides on each Data Mover.
User ID (UID)
Numeric identifier that corresponds to a particular user.
Service that automatically maps distinct Windows users and groups to distinct UNIX-style
UIDs and GIDs.
Usermapper host
Machine that runs an External Usermapper daemon or service.
See coordinated universal time.
Celerra Glossary 6.0
UTF-8 (8-bit Unicode Transformation Format)
Multibyte encoding form that uses an algorithmic mapping scheme to convert every Unicode
value to a unique 1- to 4-byte sequence with no embedded null characters.
See Unicode or UCS Transformation Format-8.
UTF-16 (16-bit Unicode Transformation Format)
Multibyte encoding form that supports the 16-bit Unicode or "wide" characters used by
Windows. UTF-16 is an extension of UCS-2.
See Universal Extended File System.
Celerra Glossary 6.0
variable length subnet mask (VLSM)
Means of specifying different subnet masks for the same network on various subnets. VLSM
maximizes the use of IP address space.
See volume based backup.
VC client
See virus-checking client.
See Virtual Data Mover.
Virtual Data Mover (VDM)
Celerra software feature that enables users to administratively separate CIFS servers, replicate
CIFS environments, and move CIFS servers from one Data Mover to another.
virtual device
Combination of multiple physical devices defined by a single MAC address.
virtual local area network (VLAN)
Group of devices physically residing on different network segments, but communicating
as if they resided on the same network segment. VLANs are configured by management
software and are based on logical connections as compared to physical connections for
increased administrative flexibility.
Virtual Provisioning
Configurable Celerra file system feature that lets you allocate storage based on long-term
projections, while you dedicate only the file system resources that you currently need.
Users—NFS or CIFS clients—and applications see the virtual maximum size of the file system
of which only a portion is physically allocated. In addition, combining the automatic file
system extension and Virtual Provisioning features lets you grow the file system gradually
as needed.
See also Automatic Volume Management.
Celerra Glossary 6.0
Virtual Storage Area Network
SAN that can be broken up into sections allowing traffic to be isolated within the section.
virtual tape library unit (VTLU)
Software-based virtual tape library configured on a Data Mover that emulates a physical
TLU. A VTLU allows NDMP to work with disk-based storage.
virtually provisioned iSCSI LUN
iSCSI LUN without reserved space on the file system. Adequate file system space must be
available for allocation whenever data is added to the LUN.
virus-checking client (VC client)
Virus-checking agent component of the Celerra Network Server software that runs on the
Data Mover.
See also AV engine, AV server, and CAVA.
virus definition file
File containing information for a virus protection program that protects a computer from
the newest, most destructive viruses. This file is sometimes referred to as a virus signature
update file, a virus pattern update file, or a virus identity (IDE) file.
See also AV engine, AV server, CAVA, and VC client.
See virtual local area network.
See variable length subnet mask.
On a Celerra system, a virtual disk into which a file system, database management system,
or other application places data. A volume can be a single disk partition or multiple partitions
on one or more physical drives.
See also disk volume, metavolume, slice volume, and stripe volume.
volume based backup (VBB)
See NDMP Volume Backup.
Volume Shadow Copy Service (VSS)
Windows service and architecture that coordinate various components to create consistent
point-in-time copies of data called shadow copies.
See Virtual Storage Area Network.
See Volume Shadow Copy Service.
Celerra Glossary 6.0
VSS provider
Component in the VSS architecture that creates and maintains shadow copies.
See virtual tape library unit.
Celerra Glossary 6.0
See wide area network.
wide area network (WAN)
Private or public network that covers a wide geographical area.
Windows domain
Microsoft Windows domain controlled and managed by a Microsoft Windows Server by
using the Active Directory to manage all system resources and by using the DNS for name
Windows Internet Naming Service (WINS)
Software service that dynamically maps IP addresses to computer names (NetBIOS names).
This allows users to access resources by name instead of requiring them to use IP addresses
that are difficult to recognize and remember. WINS servers support clients by running
Windows NT 4.0 and earlier versions of Microsoft operating systems.
Windows NT domain
Microsoft Windows domain controlled and managed by a Microsoft Windows NT server
by using a SAM database to manage user and group accounts and a NetBIOS namespace.
In a Windows NT domain, there is one primary domain controller (PDC) with a read/write
copy of the SAM, and possibly several backup domain controllers (BDCs) with read-only
copies of the SAM.
See also domain and domain controller.
See Windows Internet Naming Service.
writeable checkpoint
Read-write, point-in-time, logical image of a PFS created from a read-only (baseline)
See also production file system.
write hit
Existence of room in cache for the data presented by the write operation.
Celerra Glossary 6.0
write miss
Failed write operation due to lack of room in cache for the data presented.
Celerra Glossary 6.0
Widely used standard for defining digital certificates.
See Extensible Markup Language.
Interface for remotely managing and monitoring a Celerra Network Server. The interface
uses XML formatted messages, and is programming language neutral.
Celerra Glossary 6.0
Celerra Glossary 6.0
Set of devices that can see one another, but cannot see other devices connected to the same
connectivity product (such as a switch). In a Fibre Channel switch topology, several devices
can be grouped into zones by function or by location.
Celerra Glossary 6.0
Celerra Glossary 6.0
Special Character
Part 1 of ISO/IEC 8859, a standard character encoding of the Latin alphabet less formally
referred to as Latin-1. Each character is encoded as a single eight-bit code value.
Celerra Glossary 6.0
Special Character
Celerra Glossary 6.0