Veritas Volume Manager 4.1 Administrator's Guide (HP-UX 11i v3, February 2007)

Creating Traditional Third-Mirror Break-Off Snapshots
302 VERITAS Volume Manager Administrator’s Guide
◆ Dissociate the snapshot volume entirely from the original volume as described in
“Dissociating a Snapshot Volume (vxassist snapclear)” on page 305. 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.
Converting a Plex into a Snapshot Plex
Note The procedure described in this section cannot be used with layered volumes or any
volume that has an associated version 20 DCO volume.
It is recommended that the instant snapshot feature is used in preference to the
procedure described in this section.
In some circumstances, you may find it more convenient to convert an existing plex in a
volume into a snapshot plex rather than running vxassist snapstart. For example,
you may want to do this if you are short of disk space for creating the snapshot plex and
the volume that you want to snapshot contains more than two plexes.
The procedure can also be used to speed up the creation of a snapshot volume when a
mirrored volume is created with more than two plexes and init=active is specified.
Note It is advisable to retain at least two plexes in a volume to maintain data redundancy.
To convert an existing plex into a snapshot plex for a volume on which Persistent
FastResync is enabled, use the following command:
# vxplex [-g diskgroup] -o dcoplex=dcologplex convert \
state=SNAPDONE plex
dcologplex is the name of an existing DCO plex that is to be associated with the new
snapshot plex. You can use the vxprint command to find out the name of the DCO
volume as described in “Adding a Version 0 DCO and DCO Volume” on page 307.
For example, to make a snapshot plex from the plex trivol-03 in the 3-plex volume
trivol, you would use the following command:
# vxplex -o dcoplex=trivol_dcl-03 convert state=SNAPDONE trivol-03