Veritas Volume Manager 5.0 Administrator's Guide (September 2006)

341Administering volume snapshots
Creating traditional third-mirror break-off snapshots
Creating multiple snapshots
To make it easier to create snapshots of several volumes at the same time, the snapshot
option accepts more than one volume name as its argument, for example:
# vxassist [-g diskgroup] snapshot volume1 volume2 ...
By default, the first snapshot volume is named SNAP-volume, and each subsequent
snapshot is named SNAPnumber-volume, where number is a unique serial number, and
volume is the name of the volume for which the snapshot is being taken. This default
pattern can be overridden by using the option
-o name=pattern, as described on the
vxassist(1M) manual page. For example, the pattern
SNAP%v-%d reverses the order of
the number and volume components in the name.
To snapshot all the volumes in a single disk group, specify the option -o allvols to
vxassist:
# vxassist -g diskgroup -o allvols snapshot
This operation requires that all snapstart operations are complete on the volumes. It
fails if any of the volumes in the disk group do not have a complete snapshot plex in the
SNAPDONE state.
Reattaching a snapshot volume
Note: The information in this section does not apply to RAID-5 volumes unless they have
been converted to a special layered volume layout by the addition of a DCO and DCO
volume. See “Adding a version 0 DCO and DCO volume” on page 344 for details.
Snapback merges a snapshot copy of a volume with the original volume. One or more
snapshot plexes are detached from the snapshot volume and re-attached to the original
volume. The snapshot volume is removed if all its snapshot plexes are snapped back. This
task resynchronizes the data in the volume so that the plexes are consistent.
Note: To enhance the efficiency of the snapback operation, enable FastResync on the
volume before taking the snapshot, as described in “Enabling FastResync on a volume” on
page 284.
To merge one snapshot plex with the original volume, use the following command:
# vxassist [-g diskgroup] snapback snapshot
where snapshot is the snapshot copy of the volume.
To merge all snapshot plexes in the snapshot volume with the original volume, use the
following command:
# vxassist [-g diskgroup] -o allplexes snapback snapshot
To merge a specified number of plexes from the snapshot volume with the original
volume, use the following command:
# vxassist [-g diskgroup] snapback nmirror=number snapshot