3PAR InForm® OS 2.2.4 Concepts Guide (320-200085 Rev B, March 2009)

8.9

Virtual Volume Types and Variations

InForm OS Version 2.2.4 3PAR InForm OS Concepts Guide

Figure 8-3 illustrates one example of the possible relationships between a parent base volume

and its virtual copies, where the virtual copies are used to create additional virtual copies:

Figure 8-3. Relationships Between a Base Volume and Its Virtual Copies

See the InForm OS CLI Administrator’s Manual or the InForm OS Management Console Online

Help to learn how to create virtual copies.

8.7.3.2 Copy-on-Write Function

When a 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 data space associated with the

original virtual volume before the write operation is completed, and a pointer in the snapshot

administration space points to the copied data.

3PAR Virtual Copy supports read-only as well as read-write snapshots.

Consider an example sequence of snapshots created as illustrated in Figure 8-4 on page 8.10.

BASE VOLUME (RW)

RO RO RO RO...

RO...

RO RO RO RO...

RW = read/write

RO = read-only