Copy-On-Write Function - HP 3PAR StoreServ 7200 2-node Manual

See Figure 8 (page 47)
base volume and its virtual copies.
Figure 8 Base Volume and Virtual Copy Relationships

Copy-on-Write Function

When a virtual volume or snapshot's source volume is written to, the copy-on-write function preserves
the data that is to be overwritten. The data is copied to the snapshot space associated with the
original virtual volume before the write operation is completed, and a pointer in the administration
space points to the copied data.
See Figure 9 (page 47)
Figure 9 Snapshot Tree
In the figure above:
S0 is the first virtual copy made of BaseVV.
S2 is the most recent virtual copy.
for a more complex example of the possible relationships between a parent
for an example of a sequence of snapshots.
Virtual Copy Snapshots 47