Veritas Storage Foundation Intelligent Storage Provisioning 5.0 AdministratorÆs Guide, HP-UX 11i v3, First Edition, May 2008

104 Administering instant snapshots
Creating instant snapshots
Note: If you intend to split the clone pool that contains snapshots into
separate disk groups (for example, to perform off-host processing), the
clone pool must only contain fully synchronized full-sized instant
snapshots (which do not require a cache volume). You cannot split off a
clone pool that contains either a cache volume or space-optimized instant
snapshots.
Creating and managing space-optimized instant snapshots
Space-optimized instant snapshots are not suitable for write-intensive volumes
(such as for database redo logs) because the copy-on-write mechanism may
degrade the performance of the volume.
If you intend to split the volume and snapshot into separate disk groups (for
example, to perform off-host processing), you must use a fully synchronized
linked break-off snapshot (which does not require a cache object). You cannot
use a space-optimized instant snapshot for this purpose.
Creation of space-optimized snapshots that use a shared cache fails if the region
size specified for the volume is smaller than the region size set on the cache.
If the region size of a space-optimized snapshot differs from the region size of
the cache, this can degrade the system’s performance compared to the case
where the region sizes are the same.
Note: For space-optimized instant snapshots that share a cache object, the
specified region size must be greater than or equal to the region size specified
for the cache object.
See “Creating a shared cache volume and preparing space-optimized snapshots”
on page 97.
The attributes for a snapshot are specified as a tuple to the
vxsnap make
command. This command accepts multiple tuples; one for each snapshot that is
being created. Each element of a tuple is separated from the next by a slash
character (/). Tuples are separated by white space.