Space-optimized snapshots use a copy-on-write mechanism to make them immediately available for use when they are first created, or when their data is refreshed.

You can configure a single storage cache in a disk group that can be shared by all the volumes in that disk group. If so, the name of the cache that is declared must be the same for each volume's space-optimized snapshot. The cache is stored on disk and is persistent.

If the cache approaches full, configure VxVM to grow the cache automatically using any available free space in the disk group.

Figure: Space-optimized instant snapshot creation and usage in a backup cycle shows the instant space-optimized snapshot model.