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

9.2
Overview
3PAR InForm OS Concepts Guide InForm OS Version 2.3.1
9.1 Overview
A Common Provisioning Group (CPG) creates a virtual pool of logical disks that allows up to
4,095 virtual volumes to share the CPG's resources and allocates space on demand. You can
create fully-provisioned virtual volumes and Thinly-Provisioned Virtual Volumes (TPVVs) that
draw space from the CPG's logical disk pool.
CPGs enable fine-grained, shared access to pooled logical capacity. Instead of pre-dedicating
logical disks to volumes, the CPG allows multiple volumes to share the buffer pool of logical
disks. For example, when a TPVV is running low on user space, the system automatically assigns
more capacity to the TPVV by mapping new regions from logical disks in the CPG associated
with that TPVV. As a result, any large pockets of unused but allocated space are eliminated.
Fully-provisioned virtual volumes cannot create user space automatically and the system
allocates a fixed amount of user space for the volume.
By default, a CPG is configured to auto-grow new logical disks when the amount of available
logical disk space falls below a configured threshold. The initial buffer pool of logical disks
starts off at a fraction of the exported virtual capacity of mapped volumes and automatically
grows over time as required by application writes.
Creating CPGs can be performed with both the 3PAR InForm Command Line Interface (CLI) and
the 3PAR InForm Management Console. Refer to the 3PAR InForm OS CLI Administrator’s
Manual and the 3PAR InForm Management Console Online Help for instructions on how to
perform these tasks.
For more information about TPVVs and fully-provisioned virtual volumes, see Chapter 10,
Virtual Volumes.