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

Note: The vxsnap command provides similiar functionality for creating multiple
snapshots.
Reattaching a snapshot volume
The snapback operation merges a snapshot copy of a volume with its original.
One or more snapshot plexes are detached from the snapshot volume and
re-attached to the original volume. The snapshot volume is removed if all its
snapshot plexes are snapped back. This task resynchronizes the data in the volume
so that the plexes are consistent.
The snapback operation cannot be applied to RAID-5 volumes unless they have
been converted to a special layered volume layout by the addition of a DCO and
DCO volume.
See “Adding a version 0 DCO and DCO volume” on page 253.
To enhance the efficiency of the snapback operation, enable FastResync on the
volume before taking the snapshot
To merge one snapshot plex with the original volume, use the following command:
# vxassist [-g diskgroup] snapback snapshot
where snapshot is the snapshot copy of the volume.
To merge all snapshot plexes in the snapshot volume with the original volume,
use the following command:
# vxassist [-g diskgroup] -o allplexes snapback snapshot
To merge a specified number of plexes from the snapshot volume with the original
volume, use the following command:
# vxassist [-g diskgroup] snapback nmirror=number
snapshot
Here the nmirror attribute specifies the number of mirrors in the snapshot volume
that are to be re-attached.
Once the snapshot plexes have been reattached and their data resynchronized,
they are ready to be used in another snapshot operation.
By default, the data in the original volume is used to update the snapshot plexes
that have been re-attached. To copy the data from the replica volume instead, use
the following command:
# vxassist [-g diskgroup] -o resyncfromreplica snapback snapshot
Administering volume snapshots
Creating traditional third-mirror break-off snapshots
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