Adaptec 5325301507 - Snap Server 4400 NAS, Administrator'S Manual

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Snapshot Management and Usage
112 SnapServer Administrator Guide
Snapshot Management and Usage
This section describes snapshot components and dependencies.
The Snapshot Pool
Snapshot data are stored on a RAID in a snapshot pool , or space reserved within the
RAID for this purpose. Each RAID on the system contains only one snapshot pool.
This pool contains all snapshot data for all volumes on the RAID. For more
information, see “Estimating Snapshot Pool Requirements” on page 113.
Rolling a Volume Back to a Previous State
If you need to restore an entire file system to a previous state, you can do so without
resorting to tape. The snapshot rollback feature allows you to use any archived
snapshot to restore an entire file system to a previous state simply by selecting the
snapshot and clicking the
Rollback
button. During the rollback operation, data on
the volume will be inaccessible to clients.
Cautions
(1) Rolling back a volume cannot be undone and should only be used as a
last resort after attempts to restore selected directories or files have failed; (2)
Performing a rollback on a volume may invalidate the NetVault for GuardianOS
NVDB directory for the volume, and may also disable the antivirus software. If you
are using these features, take the necessary precautions as described in “Volumes”
on page 56.
Scheduling Snapshots
Snapshots should ideally be taken when your system is idle. It is recommended that
snapshots be taken before a backup is performed. For example, if your backup is
scheduled at 4 a.m., schedule the snapshot to be taken at 2 a.m., thereby avoiding
system activity and ensuring the snapshot is backed-up. See “Coordinating
Snapshot and Backup Operations” on page 115 for more information.
Snapshots and Backup Optimization
When you back up a live volume directly, files that reference other files in the
system may become out-of sync in relation to each other. The more data you have to
back up, the more time is required for the backup operation, and the more likely
these events are to occur. By backing up the snapshot rather than the volume itself,
you greatly reduce the risk of archiving inconsistent data. For instructions, see
“Coordinating Snapshot and Backup Operations” on page 115.