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

Creating Instant Snapshots
292 VERITAS Volume Manager Administrator’s Guide
Controlling Instant Snapshot Synchronization
Note Synchronization of the contents of a snapshot with its original volume is not
possible for space-optimized instant snapshots.
By default, synchronization is enabled for the vxsnap reattach, refresh and
restore operations on instant snapshots. Otherwise, synchronization is disabled unless
you specify the syncing=yes attribute to the vxsnap command.
The following table shows the commands that are provided for controlling the
synchronization manually.
Improving the Performance of Snapshot Synchronization
Two optional arguments to the -o option are provided to help optimize the performance
of synchronization when using the make, refresh, restore and syncstart
operations:
iosize=size Specifies the size of each I/O request that is used when
synchronizing the regions of a volume. Specifying a larger size
causes synchronization to complete sooner, but with greater impact
on the performance of other processes that are accessing the
Command Description
vxsnap [-g diskgroup] syncpause vol|vol_set Pause synchronization of a volume.
vxsnap [-g diskgroup] syncresume \
vol|vol_set
Resume synchronization of a volume.
vxsnap [-b] [-g diskgroup] syncstart \
vol|vol_set
Start synchronization of a volume. The
-b option puts the operation in the
background.
vxsnap [-g diskgroup] syncstop vol|vol_set Stop synchronization of a volume.
vxsnap [-g diskgroup] syncwait vol|vol_set Exit when synchronization of a volume
is complete. An error is returned if vol
is invalid (for example, it is a
space-optimized snapshot), or if vol is
not being synchronized.
Note You cannot use this command to
wait for synchronization of
reattached plexes to complete.