Operating System Software Owner manual

26 Virtual Volumes and CPGs
For more information, see:To create virtual volumes for Remote Copy:
1. Create a Common Provisioning Group (CPG).
• “Common Provisioning Groups” (page 187)
• HP 3PAR InForm OS CLI Administrator’s Manual
2. Create virtual volumes that draw space from that CPG
and that adhere to the rules for Remote Copy virtual
volumes.
• “Virtual Volumes Used with Remote Copy” (page 188)
• “Rules for Creating Remote Copy Virtual Volumes”
(page 189)
• HP 3PAR InForm OS CLI Administrator’s Manual
Additional Information:
• HP 3PAR InForm OS Concepts Guide
• “Modifying Virtual Volumes” (page 95)
Common Provisioning Groups
A Common Provisioning Group (CPG) is a virtual pool of logical disks that allows multiple virtual
volumes to share the CPG's resources. A CPG allocates space to its virtual volumes and/or to
snapshots on demand.
How CPGs Allocate Space for Snapshots
1. You or automatic Remote Copy processes attempt to create a new snapshot of a volume.
2. If the volume does not have enough space to create the snapshot, the system draws additional
space from the system’s common storage pool and places it into the CPG’s individual pool.
The CPG then allocates the additional space to the volume, and snapshot creation completes.
3. Remote Copy resynchronizes the volume group that contains the volume and its new snapshot
(immediately, manually, or periodically as scheduled), and then deletes the snapshot from the
system.
4. The CPG returns the space allocated to that snapshot to the volume’s free space.
NOTE: Contiguous free snapshot data space can be reclaimed and returned to the CPG
using HP 3PAR Thin Reclamation Software.
For more information about Thin Reclamation Software, see the HP 3PAR InForm OS Concepts
Guide.
How CPGs Allocate Space for Virtual Volumes
Thinly Provisioned Virtual Volumes (TPVVs)
• The system allocates space on demand to volumes as well as to
snapshots.
• When volumes draw additional space from the CPG, the volumes
become larger and require additional storage space.
To expand a volume’s storage space, the system automatically
creates additional logical disks and adds them to the CPG.
This expansion continues as necessary until the CPG reaches its
specified allocation limit.
The system cannot allocate space on demand to fully provisioned virtual
volumes. The system can only allocate space on demand to snapshots
of these volumes.
Fully provisioned virtual volumes
Common Provisioning Groups 187