Veritas Storage Foundation 5.1 SP1 Advanced Features Administrator"s Guide (5900-1503, April 2011)

To create instant snapshots of volume sets, use volume set names in place of
volume names in the vxsnap command.
See “Creating instant snapshots of volume sets” on page 229.
When using the vxsnap prepare or vxassist make commands to make a volume
ready for instant snapshot operations, if the specified region size exceeds half
the value of the tunable voliomem_maxpool_sz , the operation succeeds but gives
a warning such as the following (for a system where voliomem_maxpool_sz is set
to 12MB):
VxVM vxassist WARNING V-5-1-0 Specified regionsize is
larger than the limit on the system
(voliomem_maxpool_sz/2=6144k).
If this message is displayed, vxsnap make, refresh and restore operations on
such volumes fail as they might potentially hang the system. Such volumes can
be used only for break-off snapshot operations using the reattach and make
operations.
To make the volumes usable for instant snapshot operations, use vxsnap
unprepare on the volume, and then use vxsnap prepare to re-prepare the volume
with a region size that is less than half the size of voliomem_maxpool_sz (in this
example, 1MB):
# vxsnap -g mydg -f unprepare vol1
# vxsnap -g mydg prepare vol1 regionsize=1M
See “Creating instant snapshots of volume sets” on page 229.
See “Creating and managing space-optimized instant snapshots” on page 218.
See “Creating and managing full-sized instant snapshots” on page 221.
See “Creating and managing third-mirror break-off snapshots” on page 223.
See “Creating and managing linked break-off snapshot volumes” on page 226.
213Administering volume snapshots
Creating instant snapshots