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

339Administering volume snapshots
Creating traditional third-mirror break-off snapshots
For example, to create a snapshot of voldef, use the following command:
# vxassist [-g diskgroup] snapshot voldef snapvol
The vxassist snapshot task detaches the finished snapshot mirror, creates a new
volume, and attaches the snapshot mirror to it. This step should only take a few
minutes. The snapshot volume, which reflects the original volume at the time of the
snapshot, is now available for backing up, while the original volume continues to be
available for applications and users.
If required, you can make snapshot volumes for several volumes in a disk group at
the same time. See “Creating multiple snapshots” on page 341 for more information.
4Use fsck (or some utility appropriate for the application running on the volume) to
clean the temporary volume’s contents. For example, you can use this command with
a VxFS file system:
# fsck -F vxfs /dev/vx/rdsk/diskgroup/snapshot
5 If you require a backup of the data in the snapshot, use an appropriate utility or
operating system command to copy the contents of the snapshot to tape, or to some
other backup medium.
When the backup is complete, you have the following choices for what to do with the
snapshot volume:
■ Reattach some or all of the plexes of the snapshot volume with the original volume as
described in “Reattaching a snapshot volume” on page 341. If FastResync was
enabled on the volume before the snapshot was taken, this speeds resynchronization
of the snapshot plexes before the backup cycle starts again at step 3.
■ Dissociate the snapshot volume entirely from the original volume as described in
“Dissociating a snapshot volume” on page 343. This may be useful if you want to use
the copy for other purposes such as testing or report generation.
■ Remove the snapshot volume to save space with this command:
# vxedit [-g diskgroup] -rf rm snapshot
Note: Dissociating or removing the snapshot volume loses the advantage of fast
resynchronization if FastResync was enabled. If there are no further snapshot plexes
available, any subsequent snapshots that you take require another complete copy of
the original volume to be made.