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

Traditional Third-Mirror Break-Off Snapshots
264 VERITAS Volume Manager Administrator’s Guide
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 274 for more information.
As described in “FastResync” on page 49, 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 299 for a
description of the procedures for creating and using this type of snapshot.