For a traditional, third-mirror break-off snapshot, you can convert an existing plex in a volume into a snapshot plex. Symantec recommends using the instant snapshot feature rather than 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.

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.

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.

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_dco-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.