Managing Cpgs And Virtual Volumes; Overview; Common Provisioning Groups; Growth Increment Considerations For Common Provisioning Groups - HP 3PAR StoreServ 7200 2-node Administrator's Manual

6 Managing CPGs and Virtual Volumes

Overview

A CPG creates a virtual pool of LDs that allows up to 4,095 virtual volumes to share the CPG's
resources and to allocate space on demand. Virtual volumes draw their resources from CPGs, and
virtual volumes are exported as Logical Unit Numbers (LUNs) to hosts. Virtual volumes are the only
data layer visible to hosts. You can create physical copies or virtual copy snapshots of virtual
volumes for use if the original base volume becomes unavailable. Before creating virtual volumes,
you must first create CPGs to allocate space to the virtual volumes.
The system allows you to create a maximum of 2,048 CPGs on one system. For the maximum
number of virtual volumes that can be created with your specific system configuration, go to the
HP SPOCK website:
http://www.hp.com/storage/spock
For detailed information about CPGs and virtual volumes, see the HP 3PAR StoreServ Storage
Concepts Guide.
For instructions on how to create copies of volumes, see
(page 95).
NOTE: Creating TPVVs requires the HP 3PAR Thin Provisioning Software license. Creating virtual
copies or snapshots requires the HP 3PAR Virtual Copy Software license. Contact your HP
representative for more information.

Common Provisioning Groups

By default, a CPG is configured to auto-grow new LDs when the amount of available LD space
falls below a configured threshold. CPGs are initially empty. The initial buffer pool of LDs starts off
at a fraction of the exported virtual capacity of mapped volumes and automatically grows over
time, as required by application writes. For detailed information about CPG growth warnings and
growth limits, see the HP 3PAR StoreServ Storage Concepts Guide.
NOTE: Virtual volumes in the same CPG can share the same LD. In the unlikely event that the LD
is damaged by multiple simultaneous disk failures, all the volumes associated with that LD will be
unavailable.
Virtual volume performance may suffer from too much interleaving within the LDs.

Growth Increment Considerations for Common Provisioning Groups

The default and minimum growth increments vary according to the number of controller nodes in
the system.
Table 6 Default and Minimum Growth Increments
Number of nodes
2
4
6
8
78 Managing CPGs and Virtual Volumes
Default
32 GB
64 GB
96 GB
128 GB
"Managing Virtual Volume Copies"
Minimum
8 GB
16 GB
24 GB
32 GB