Dell PowerVault ME5 Series Administrator's Guide

Internal snapshots

When first created from the primary volume, the internal snapshots consume very little space but will grow as data is written to the volume. Just as with any virtual snapshot, the amount of disk space used by an internal snapshot depends on the difference in the number of shared and unique pages between itself and the volume. The snapshot will not exceed the amount of disk space used by the primary volume. At most, the two internal snapshots together for each volume may consume twice the amount of disk space as the primary volume from which they are snapped.

Even though the internal snapshots are hidden from the user, they do consume snapshot space (and thus pool space) from the virtual pool. If the volume is the base volume for a snapshot tree, the count of maximum snapshots in the snapshot tree may include the internal snapshots for it even though they are not listed. Internal snapshots and internal volume groups count against system limits, but do not display.