HPE 3PAR Virtual Copies or snapshots are used to provide a point-in-time virtual copy of a VV and ensure that the original data can always be obtained should a problem occur when updating the data on a VV. HPE 3PAR Virtual Copies rely on an efficient COW mechanisms (copy-on-write) called Delayed copy-on-write (DCOW) to improve performance from the host perspective. HPE 3PAR Virtual Copies are always thin, non-duplicative (only one copy of the change blocks is kept and then referenced) and reservationless, they can also have variable quality of service as the user can specify a different CPG for snapshot data.