HP Veritas Volume Manager 5.0 -UX 11i v3 manual Creating multiple snapshots

Administering volume snapshots 317

Creating multiple snapshots

Figure 9-8

Original volume

V

Splitting snapshots

Snapshot

volume of V:

S1

vxsnap split S1

Snapshot

volume of S1:

S2

Original volume

V

Volume

S1

S1 is independent

Snapshot

volume of S1:

S2

S2 continues to be a

snapshot of S1

Creating multiple snapshots

To make it easier to create snapshots of several volumes at the same time, both the vxsnap make and vxassist snapshot commands accept more than one volume name as their argument.

For traditional snapshots, you can create snapshots of all the volumes in a single disk group by specifying the option -o allvols to the vxassist snapshot command.

By default, each replica volume is named SNAPnumber-volume, where number is a unique serial number, and volume is the name of the volume for which a snapshot is being taken. This default can be overridden by using the option -o name=pattern, as described on the vxsnap(1M) and vxassist(1M) manual pages.

It is also possible to take several snapshots of the same volume. A new FastResync change map is produced for each snapshot taken to minimize the resynchronization time for each snapshot.

Restoring the original volume from a snapshot

For traditional snapshots, the snapshot plex is resynchronized from the data in the original volume during a vxassist snapback operation. Alternatively, you can choose the snapshot plex as the preferred copy of the data when performing a snapback as illustrated in Figure 9-9. Specifying the option -o resyncfromreplica to vxassist resynchronizes the original volume from the data in the snapshot.