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Using a DCO and DCO volume with a RAID-5 volume

The procedure in the previous section can be used to add a DCO and DCO volume to a RAID-5 volume. This allows you to use Persistent FastResync on the volume for fast resynchronization of snapshots on returning them to their original volume. However, the procedure has the side effect of converting the RAID-5 volume into a special type of layered volume. You can create space-optimized instant snapshots of such a volume, and you can add mirrors that may be broken off as full-sized instant snapshots. You cannot relayout or resize such a volume unless you convert it back to a pure RAID-5 volume.

To convert a volume back to a RAID-5 volume, remove any snapshot plexes from the volume, and dissociate the DCO and DCO volume from the layered volume. You can then perform relayout and resize operations on the resulting non-layered RAID-5 volume.

See "Removing support for DRL and instant snapshots from a volume" on page 289.

To allow Persistent FastResync to be used with the RAID-5 volume again, re-associate the DCO and DCO volume.

See "Preparing a volume for DRL and instant snapshots" on page 285.

Warning: Dissociating a DCO and DCO volume disables FastResync on the volume. A full resynchronization of any remaining snapshots is required when they are snapped back.