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

Creating Instant Snapshots
278 VERITAS Volume Manager Administrator’s Guide
# vxsnap [-b] [-g diskgroup] addmir volume [nmirror=N] \
[alloc=storage_attributes]
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 To turn one or more existing plexes in a volume into a break-off instant
snapshot volume, the volume must be a non-layered volume with a mirror or
mirror-stripe layout, or a RAID-5 volume that you have converted to a
special layered volume (see “Using a DCO and DCO Volume with a RAID-5
Vol um e” on page 237) and then mirrored. The plexes in a volume with a
stripe-mirror layout are mirrored at the sub-volume level, and cannot be
broken off.
4. Use the vxsnap make step to create an instant snapshot that is immediately available
for making a backup. If you specify a name and size for a storage cache, a
space-optimized snapshot is created that requires less space than does a full-sized
snapshot volume.
Depending on the type of instant snapshot that you require, there are three main
variants on the vxsnap make command that you can issue:
❖ To create a full-sized instant snapshot, use one of the following forms of the vxsnap
make command:
# vxsnap [-g diskgroup] make source=volume/snapvol=snapvol\
[/syncing=off]
# vxsnap [-g diskgroup] make source=volume[/newvol=snapvol]\
{/plex=plex1[,plex2,...]|/nmirror=number]}
Note The attributes for a snapshot are specified as a tuple. The vxsnap make
command accepts multiple tuples; one for each snapshot that is being created.
A tuple for a full-sized instant snapshot must contain a source attribute and a
snapvol attribute. Each element of a tuple is separated from the next by a slash
character (/). Tuples are separated by white space.