Emulation of third-mirror break-off snapshots

Third-mirror break-off snapshots are suitable for write-intensive volumes (such as for database redo logs) where the copy-on-write mechanism of space-optimized or full-sized instant snapshots might degrade performance.

If you use the vxsnap prepare command to enable a volume for use with instant and space-optimized snapshots, you cannot use the vxassist snapshot commands to administer snapshots that you create for that volume. If you require snapshots that behave as third-mirror break-off snapshots (that is, they must be fully synchronized before they can be used), there are three ways to achieve this:

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Traditional third-mirror break-off snapshots

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

Adding snapshot mirrors to a volume

Creating and managing third-mirror break-off snapshots