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Note
The information in this section does not apply 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 for details.
Snapback merges a snapshot copy of a volume with the original volume. 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.
Note
To enhance the efficiency of the snapback operation, enable FastResync on the volume before taking the snapshot, as described in Enabling FastResync on a volume.
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
Caution
Always unmount the snapshot volume (if mounted) before performing a snapback. In addition, you must unmount the file system corresponding to the primary volume before using the resyncfromreplica option.