Veritas Volume Manager 5.0 Administrator's Guide (September 2006)

318 Administering volume snapshots
Creating instant snapshots
# vxsnap -g mydg syncwait snap2myvol
This command exits (with a return code of zero) when synchronization of the
snapshot volume is complete. The snapshot volume may then be moved to another
disk group or turned into an independent volume.
If required, you can use the following command to test if the synchronization of a
volume is complete:
# vxprint [-g diskgroup] -F%incomplete snapvol
This command returns the value off if synchronization of the volume, snapvol, is
complete; otherwise, it returns the value on.
You can also use the vxsnap print command to check on the progress of
synchronization as described in “Displaying instant snapshot information” on
page 331.
See “Controlling instant snapshot synchronization” on page 333 for more
information.
If you do not want to move the snapshot into a separate disk group, or to turn it into
an independent volume, specify the
syncing=off attribute. This avoids creating
unnecessary system overhead. For example, to turn off synchronization when
creating the snapshot of the volume, myvol, you would use the following form of
the
vxsnap make command:
# vxsnap -g mydg make source=myvol/snapvol=snap1myvol\
/syncing=off
2Use fsck (or some utility appropriate for the application running on the volume) to
clean the temporary volume’s contents. For example, you can use this command with
a VxFS file system:
# fsck -F vxfs /dev/vx/rdsk/diskgroup/snapshot
3 If you require a backup of the data in the snapshot, use an appropriate utility or
operating system command to copy the contents of the snapshot to tape, or to some
other backup medium.
4 You now have the following choices of what to do with a full-sized instant snapshot:
■ Refresh the contents of the snapshot. This creates a new point-in-time image of
the original volume ready for another backup. If synchronization was already in
progress on the snapshot, this operation may result in large portions of the
snapshot having to be resynchronized. See “Refreshing an instant snapshot” on
page 327 for details.
■ Reattach some or all of the plexes of the snapshot volume with the original
volume. See “Reattaching an instant snapshot” on page 327 for details.
■ Restore the contents of the original volume from the snapshot volume. You can
choose whether none, a subset, or all of the plexes of the snapshot volume are
returned to the original volume as a result of the operation. See “Restoring a
volume from an instant snapshot” on page 329 for details.