HP StoreAll Storage - Manual (Page 367)

21 Creating block snapshots
Overview
The block 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.
NOTE: You can use either the software method or the block method to take snapshots on a file
system. Using both snapshot methods simultaneously on the same file system is not supported.
The block snapshot feature is supported as follows:
•
HP 9320 Storage: supported on the HP P2000 G3 MSA Array System or HP 2000 Modular
Smart Array G2 provided with the platform.
•
HP 9300 Storage Gateway: supported on the HP P2000 G3 MSA Array System; HP 2000
Modular Smart Array G2; HP P4000 G2 Models; HP 3PAR F200, F400, T400 and T800s
Storage Systems (OS version 2.3.1 (MU3); and Dell EqualLogic storage array—no arrays are
provided with the 9300 system).
•
HP 8200 Storage Gateway: HP 3PAR P7000 (7200, 7400), P10000, and T400/T800
Storage Systems
•
HP X9720/9730 Storage: no support.
NOTE: Creating block snapshots on an HP StoreAll file system using 3PAR virtual volume sets
(VVSET) is not supported. Two or more virtual volumes (VV) can be combined to form a VVSET.
See the appropriate 3PAR documentation for more information about virtual volumes and virtual
volume sets.
NOTE: To create block snapshots on an HP 8200 Storage with HP 3PAR storage, virtual volumes
must be created on the 3PAR storage and exported to a host set that contains both servers in the
cluster. The 3PAR Management Console can be used for 3PAR storage configuration. The export
to the host set is required for block snapshots to work on HP 8200 Storage with 3PAR.
The block 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.
You can take snapshots via the StoreAll software block snapshot 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.
Overview 367