3PAR InForm® OS 2.3.1 Concepts Guide (320-200112 Rev B, February 2010)

2.5
3PAR Storage Concepts and Terminology
InForm OS Version 2.3.1 3PAR InForm OS Concepts Guide
2.1.5 Virtual Volumes
Virtual volumes draw their resources from Common Provisioning Groups (CPGs), and volumes
are exported as Logical Unit Numbers (LUNs) to hosts. Virtual volumes are the only data layer
visible to the hosts. You can create physical copies or virtual copy snapshots of virtual volumes
that remain available if the original base volume becomes unavailable. Before creating virtual
volumes, you must first create CPGs to allocate space to the virtual volumes. For more
information about virtual volumes, see Chapter 10, Virtual Volumes.
2.1.5.1 Fully-Provisioned Virtual Volumes
A fully-provisioned virtual volume is a volume that uses logical disks that belong to a logical
disk pool known as a Common Provisioning Group (CPG). Unlike Thinly-Provisioned Virtual
Volumes (TPVVs), fully-provisioned virtual volumes have a set amount of user space that is
allocated for user data. The fully-provisioned volume size is fixed, and the size limit is 16 TB.
For more information about fully-provisioned virtual volumes, Fully-Provisioned Virtual
Volumes on page 10.3.
2.1.5.2 Thinly-Provisioned Virtual Volumes
A Thinly-Provisioned Virtual Volume (TPVVs) is a volume that uses logical disks that belong to a
logical disk pool known as a Common Provisioning Group (CPG). TPVVs associated with the
same CPG draw space from that pool as needed, allocating space on demand in small
increments beginning with 256 MB for each controller node. As the volumes that draw space
from the CPG require additional storage, the InForm OS automatically creates additional
logical disks and adds them to the pool until the CPG reaches the user-defined growth limit
which restricts the CPG’s maximum size. The TPVV volume size limit is 16 TB. For more
information about TPVVs, see Thinly-Provisioned Virtual Volumes on page 10.4.
NOTE: Creating Thinly-Provisioned Virtual Volumes (TPVVs) requires the 3PAR
Thin Provisioning license. For more information, see 3PAR InForm Software on
page 2.7.