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

2.7
3PAR Storage Concepts and Terminology
InForm OS Version 2.2.4 3PAR InForm OS Concepts Guide
2.1.3 Virtual Volumes
Virtual volumes can either be base volumes or snapshots (copies of other volumes). Copies of
other volumes are called snapshots because they are point-in-time copies. These snapshots can
either be virtual copies or physical copies. A virtual copy is a snapshot created using the 3PAR
copy-on-write technique and a physical copy is a point-in-time copy of an entire base volume.
All types of volumes are created by mapping data from one or more logical disks to the virtual
volume. Mapping is the correspondence of logical disk regions to virtual volume regions. The
logical disks can either be created by the system when the volume is created, or allocated from
a common provisioning group.
2.1.3.1 Base Volumes
Figure 2-4 shows data mapped in regions from logical disks onto a base volume.
Figure 2-4. Data is Mapped from Logical Disks onto a Virtual Volume in Regions
NOTE: Snapshot administration space is explained in a following section. CPGs are
explained further in Chapter 10, Common Provisioning Groups.
AA
DD
BB
EE
CC
FF
A
P (E,F)
B
E
P (A,B)
F
C
P (G,H)
D
G
P (C,D)
H
AA BBCCDDEE FF A B C D E F
Region
Logical disk (RAID 5)
Virtual volume
Region
Logical disk (RAID 1)
VV
VV
RAID set
LD
Region
Chunklet
Mirror
LD
Region
NOTE: Virtual volumes and virtual volume types are discussed in further detail in
Chapter 8, Virtual Volumes.