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NetBackup™ Snapshot Client Administrator's Guide

Last Published: 2022-05-23

Product(s): NetBackup & Alta Data Protection (10.0)

terminology

Table: terminology describes the terms that are used with NetBackup . For explanations of other NetBackup terms, consult the NetBackup online glossary.

Table: terminology

Term	Definition
SMDC
Alternate client backup	The alternate client performs a backup on behalf of another client.
Backup agent (see also Third-Party Copy Device)	A general term for the host that manages the backup on behalf of the NetBackup client. The agent is either another client, the NetBackup media server, a third-party copy device, or a NAS filer.
BCV	The mirror disk in an EMC primary-mirror array configuration (see mirror). BCV stands for Business Continuance Volume.
Bridge	In a SAN network, a bridge connects SCSI devices to Fibre Channel. A third-party copy device can be implemented as part of a bridge or as part of other devices. Note that not all bridges function as third-party copy devices.
Cache	Copy-on-write snapshot methods need a separate working area on disk during the lifetime of the snapshot. This area is called a cache. The snapshot method uses the cache to store a copy of the client's data blocks that are about to change because of file system activity. This cache must be a raw disk partition that does not contain valuable information: when you use the cache, the snapshot method overwrites any data currently stored there. See How copy-on-write works.
Copy Manager	See Third-Party Copy Device.
Copy-on-write	In NetBackup , one of two types of supported snapshots (see also mirror). Unlike a mirror, a copy-on-write does not create a separate copy of the client's data. It creates a block-by-block "account" from the instant the copy-on-write was activated. The account describes which blocks in the client data have changed and which have not. The backup application uses this account to create the backup copy. Other terms and trade names sometimes used for copy-on-write snapshots are space-optimized snapshots, space-efficient snapshots, and checkpoints.
Data movement	A copy operation as performed by a third-party copy device or NetBackup media server.
Data mover	The host or entity that manages the backup on behalf of the NetBackup client. The data mover can be either the NetBackup media server, a third-party copy device, or a NAS filer.
device	A general term for any of the following: LUN, logical volume, vdisk, and BCV or STD.
Disk group	A configuration of disks to create a primary-mirror association, using commands unique to the disks' vendor. See mirror and volume group.
Extent	A contiguous set of disk blocks that are allocated for a file and represented by three values: Device identifier Starting block address (offset in the device) Length (number of contiguous blocks) The mapping methods in determine the list of extents and send the list to the backup agent.
Fibre Channel	A type of high-speed network that is composed of either optical or of copper cable and employing the Fibre Channel protocol. NetBackup supports both arbitrated loop and switched fabric (switched Fibre Channel) environments.
File system
Instant Recovery	A restore feature of a disk snapshot of a client file system or volume. Client data can be rapidly restored from the snapshot, even after a system restart.
Mapping	Converting a file or raw device (in the file system or Volume Manager) to physical addresses or extents for backup agents on the network. NetBackup uses the VxMS library to perform file mapping.
Mapping methods	A set of routines for converting logical file addresses to physical disk addresses or extents. NetBackup includes support for file-mapping and volume-mapping methods.
Mirror	Has two meanings. A disk that maintains an exact copy or duplicate of another disk. A mirror disk is often called a secondary, and the source disk is called the primary. All writes to the primary disk are also made to the mirror disk. A type of snapshot that is captured on a mirror disk. At an appropriate moment, all further writes to the primary disk are held back from the mirror, which "splits" the mirror from the primary. As a result of the split, the mirror becomes a snapshot of the primary. The snapshot can then be backed up.
NetBackup media server method	An off-host backup method in which the NetBackup media server performs the data movement.
Off-host backup	The off-loading of backup processing to a separate backup agent executing on another host. NetBackup provides the following off-host backup options: Alternate Client, NetBackup media server, Third-Party Copy Device, and Network Attached Storage.
Primary disk	In a primary-mirror configuration, client applications read and write their data on the primary disk. An exact duplicate of the primary disk is the mirror.
Raw partition	A single section of a raw physical disk device occupying a range of disk sectors. The raw partition does not have a file system or other hierarchical organization scheme (thus, a "raw" stream of disk sectors). On some operating systems, such as Solaris and HP-UX, a raw partition is different from a block device over which the file system is mounted.
Recovery Manager (RMAN)	Oracle's backup and recovery program. RMAN performs backup and restore by making requests to a NetBackup shared library.
RMAN Proxy Copy	An extension to the Oracle8i media management API which enables media management software such as NetBackup to perform data transfer directly.
SAN (storage area network)	A Fibre Channel-based network connecting servers and storage devices. The storage devices are not attached to servers but to the network itself, and are visible to all servers on the network.
Secondary disk	See mirror.
Third-Party Copy Device	Has two meanings: A backup agent on the SAN that operates on behalf of backup applications. The third-party copy device receives backup data from a disk that is attached to Fibre Channel and sends it to a storage device. The third-party copy device uses the SCSI Extended Copy command. The third-party copy device is sometimes called a Copy Manager, third-party copy engine, or data mover. In SAN hardware configurations, a third-party copy device can be implemented as part of a bridge, router, or storage device. The third-party copy device may or may not be the device to which the storage units are connected. An off-host backup method in NetBackup that allows backups to be made by means of a backup agent on the SAN.
VxMS (Veritas Federated Mapping Services)	A library of routines (methods) used by NetBackup to obtain the physical addresses of logical disk objects such as files and volumes.
Volume	A virtual device that is configured over raw physical disk devices (not to be confused with a NetBackup Media and Device Management volume). Consists of a block and a character device. If a snapshot source exists over a volume, NetBackup automatically uses a volume mapping method to map the volume to physical device addresses.
Volume group	A logical grouping of disks, created with the Veritas Volume Manager, to allow more efficient use of disk space.

More Information

About snapshot management

About snapshot basics

Benefits of copy-on-write versus mirror

About local backup of a snapshot

Off-host backup overview

Off-host backup methods

requirements

assistance

About open file backups for Windows