VERITAS Volume Manager 3.5 Administrator's Guide (September 2002)

Chapter 8, Administering Volumes
Backing up Volumes Online
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Note Dissociating or removing the snapshot volume loses the advantage of fast
resynchronizationif FastResync was enabled.Ifthereareno further snapshot plexes
available, any subsequent snapshots that you take requireanother completecopy of
the original volume to be made.
Converting a Plex into a Snapshot Plex
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.
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] 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 DCO and DCO Volume” on page 193.
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 dcoplex=trivol_dcl-03 convert state=SNAPDONE trivol-03
Here the DCO plex trivol_dco_03 is specified as the DCO plex for the new snapshot
plex.
To convert an existing plex into a snapshot plex in the SNAPDONE state for a volume on
which Non-Persistent FastResync is enabled, use the following command:
# vxplex [-g diskgroup] convert state=SNAPDONE plex
A converted plex is in the SNAPDONE state, and can be used immediately to create a
snapshot volume.
Note The last complete regular plex in a volume, an incomplete regular plex, or a dirty
region logging (DRL) log plex cannot be converted into a snapshot plex.