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

Creating Instant Snapshots
286 VERITAS Volume Manager Administrator’s Guide
By default, the vxsnap addmir command adds one snapshot mirror to a volume unless
you use the nmirror attribute to specify a different number of mirrors. The mirrors
remain in the SNAPATT state until they are fully synchronized. The -b option can be used
to perform the synchronization in the background. Once synchronized, the mirrors are
placed in the SNAPDONE state.
For example, the following command adds 2 mirrors to the volume, vol1, on disks
mydg10 and mydg11:
# vxsnap -g mydg addmir vol1 nmirror=2 alloc=mydg10,mydg11
Note This command is similar in usage to the vxassist snapstart command, and
supports the traditional third-mirror break-off snapshot model. As such, it does not
provide an instant snapshot capability.
Once you have added one or more snapshot mirrors to a volume, you can use the vxsnap
make command with either the nmirror attribute or the plex attribute to create the
snapshot volumes.
Removing a Snapshot Mirror from a Volume
To remove a single snapshot mirror from a volume, use this command:
# vxsnap [-g diskgroup] rmmir volume|volume_set
For example, the following command removes a snapshot mirror from the volume, vol1:
# vxsnap -g mydg rmmir vol1
Note This command is similar in usage to the vxassist snapabort command.
If a volume set name is specified instead of a volume, a mirror is removed from each
volume in the volume set.
Adding a Snapshot to a Cascaded Snapshot Hierarchy
To create a snapshot and push it onto a snapshot hierarchy between the original volume
and an existing snapshot volume, specify the name of the existing snapshot volume as the
value of the infrontof attribute to the vxsnap make command. The following example
shows how to place the space-optimized snapshot, thurs_bu, of the volume, dbvol, in
front of the earlier snapshot, wed_bu:
# vxsnap -g dbdg make source=dbvol/newvol=thurs_bu/\
infrontof=wed_bu/cache=dbdgcache