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Reattaching an instant snapshot

  Note   This operation is not supported for space-optimized instant snapshots.

Using the following command, some or all plexes of an instant snapshot may be reattached to the specified original volume, or to a source volume in the snapshot hierarchy above the snapshot volume:

# vxsnap [-g diskgroup] reattach snapvolume|snapvolume_set \

  source=volume|volume_set [nmirror=number]

By default, all the plexes are reattached, which results in the removal of the snapshot. If required, the number of plexes to be reattached may be specified as the value assigned to the nmirror attribute.

Warning: The snapshot that is being reattached must not be open to any application. For example, any file system configured on the snapshot volume must first be unmounted.

It is possible to reattach a volume to an unrelated volume provided that their volume sizes and region sizes are compatible.

For example the following command reattaches one plex from the snapshot volume, snapmyvol, to the volume, myvol:

# vxsnap -g mydg reattach snapmyvol source=myvol nmirror=1

While the reattached plexes are being resynchronized from the data in the parent volume, they remain in the SNAPTMP state. After resynchronization is complete, the plexes are placed in the SNAPDONE state. You can use the vxsnap snapwait command (but not vxsnap syncwait) to wait for the resynchronization of the reattached plexes to complete, as shown here:

# vxsnap -g mydg snapwait myvol nmirror=1

If the volume and its snapshot have both been resized (to an identical smaller or larger size) before performing the reattachment, a fast resynchronization can still be performed. A full resynchronization is not required. Version 20 DCO volumes are resized proportionately when the associated data volume is resized. For version 0 DCO volumes, the FastResync maps stay the same size, but the region size is recalculated, and the locations of the dirty bits in the existing maps are adjusted. In both cases, new regions are marked as dirty in the maps.