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

298 Administering volume snapshots
Traditional third-mirror break-off snapshots
the snapshot. If more than one snapshot mirror is used, the snapshot volume is itself
mirrored.
The command, vxassist snapback, can be used to return snapshot plexes to the
original volume from which they were snapped, and to resynchronize the data in the
snapshot mirrors from the data in the original volume. This enables you to refresh the data
in a snapshot after each time that you use it to make a backup. You can also use a variation
of the same command to restore the contents of the original volume from a snapshot that
you took at an earlier point in time. See “Restoring the original volume from a snapshot”
on page 308 for more information.
As described in “FastResync” on page 66, you can use the FastResync feature of VxVM to
minimize the time needed to resynchronize the data in the snapshot mirror. If FastResync
is not enabled, a full resynchronization of the data is required.
Finally, you can use the
vxassist snapclear command to break the association
between the original volume and the snapshot volume. The snapshot volume then has an
existence that is independent of the original volume. This is useful for applications that do
not require the snapshot to be resynchronized with the original volume.
Note: The use of the vxassist command to administer traditional (third-mirror break-
off) snapshots is not supported for volumes that are prepared for instant snapshot creation.
Instead, the vxsnap command may be used as described in the following section.
See “Creating traditional third-mirror break-off snapshots” on page 337 for a description
of the procedures for creating and using this type of snapshot.