SFW supports Microsoft Copy on Write (COW) snapshots. The VEA GUI or the vxsnap CLI utility can be used to take COW snapshots. Microsoft COW snapshots are faster than full snapshots and take up less storage space.

A COW snapshot creates a shadow copy that is differential. When a change to the original volume occurs, the block that is about to be modified is read and then written to a "differences area", which preserves a copy of the data block before it is overwritten with the change. This approach stores a copy of the block before it is changed. Using the blocks in the differences area and unchanged blocks in the original volume, a copy of the volume can be constructed that represents the volume in the state before any changes occurred.

The benefit of the COW snapshot is that it creates shadow copies very rapidly because it writes only the changed blocks at a given time.