5.6 HP StorageWorks X9000 File Serving Software User Guide (TA768-96035, June 2011)

12 Creating snapshots
The snapshot feature allows you to capture a point-in-time copy of a file system for online backup
purposes and to simplify recovery of files from accidental deletion. The snapshot replicates all file
system entities at the time of capture and is managed exactly like any other file system.
The snapshot feature is supported as follows:
• HP StorageWorks X9320 Network Storage System: supported on the HP StorageWorks P2000
G3 MSA Array System or HP StorageWorks 2000 Modular Smart Array G2 provided with
the platform.
• HP StorageWorks X9300 Network Storage Gateway: supported on the HP StorageWorks
P2000 G3 MSA Array System, HP StorageWorks 2000 Modular Smart Array G2, and Dell
EqualLogic storage array (no arrays are provided with the X9300 system).
• HP StorageWorks X9720 Network Storage System: no support.
The snapshot feature uses the copy-on-write method to preserve the snapshot regardless of changes
to the origin file system. Initially, the snapshot points to all blocks that the origin file system is using
(B in the following diagram). When a block in the origin file system is overwritten with additions,
edits, or deletions, the original block (prior to changes) is copied to the snapshot store, and the
snapshot points to the copied block (C in the following diagram). The snapshot continues to point
to the origin file system contents from the point in time that the snapshot was executed.
To create a snapshot, first provision or register the snapshot store. You can then create a snapshot
from type-specific storage resources. The snapshot is active from the moment it is created.
You can take snapshots via the X9000 Software scheduler or manually, whenever necessary. Each
snapshot maintains its origin file system contents until deleted from the system.
Snapshots can be made visible to users, allowing them to access and restore files (based on
permissions) from the available snapshots.
NOTE: By default, snapshots are read only. HP recommends that you do not allow writes to any
snapshots.
Setting up snapshots
This section describes how to configure the cluster to take snapshots.
Preparing the snapshot partition
The snapshot feature does not require any custom settings for the partition. However, HP recommends
that you provide sufficient storage capacity to support the snapshot partition.
96 Creating snapshots