Veritas Storage Foundation Intelligent Storage Provisioning 5.0.1 Administrators Guide, HP-UX 11i v3, First Edition, November 2009

I/O performance for critical volumes, or hindering disk group split and
join operations.
2
Use the following vxassist command to create the cache volume:
# vxassist [-g diskgroup] [-P storage_pool] make cachevol \
size [storage_specification ...] [attribute ...] \
[regionsize size] type=cachevolume
The attribute regionsize specifies the minimum size of each chunk (or region)
of a volume whose contents are tracked for changes. The region size must be
a power of 2, and be greater than or equal to 16 KB. A smaller value requires
more disk space for the change maps, but the finer granularity provides faster
resynchronization. The default region size is 64 K (64 KB).
The following example creates a 1 GB mirrored cache volume, cachevol, in
the clone storage pool, myclpool, within the disk group, mydg:
# vxassist -g mydg -P myclpool make mycache 1g \
rules="mirror 2" type=cachevolume
3
Use the following command to prepare each space-optimized snapshot that
uses the cache volume:
# vxassist [-g diskgroup] [-P storage_pool] make sovol \
srcvol_len [storage_specification ...] [attribute ...] \
type=snapshot cachevolume=cachevol init=active
The srcvol_len argument specifies the length of the source volume for which
the snapshot is being prepared. This value defines the logical size of the
snapshot. The actual amount of storage that the snapshot requires is less
than this, and is limited by the size of the cache volume.
For example, the following command creates a space-optimized snapshot
volume that uses the cache volume, mycache:
# vxassist -g mydg -P myclpool make mysovol 10g \
type=snapshot cachevolume=mycache
The argument 10g is the size of the source volume for which the snapshot
mysovol is being prepared.
Once created, such a volume is ready for use to take a space-optimized instant
snapshot.
103Administering instant snapshots
Creating a shared cache volume and preparing space-optimized snapshots