HP 3PAR StoreServ Concepts Guide: HP 3PAR OS 3.1.3

controller node 0, when the virtual volumes that draw from a CPG have filled up all space available
to that CPG based on its LD parameters, the following will happen:
• New writes to any TPVVs that are mapped to that CPG will return write failures.
• Snapshot volumes mapped to the CPG may become invalid (stale), subject to the virtual copy
policy associated with the base volume. For base volumes with a no stale snapshots
virtual copy policy, new writes to the base volume will result in write failures.
• For base volumes with a stale snapshots virtual copy policy, new writes will cause
snapshot volumes to become invalid (stale).
• If the volumes that draw from a CPG reach the CPG growth limit, the system generates
additional alerts to notify you that all logical capacity for the CPG has been consumed.
System Guidelines for Creating CPGs
Use the following guidelines to ensure maximum performance and optimal reliability in the volumes
supported by those LDs:
• To provide the highest availability, chunklets in the same RAID set should be from different
drive cages, and then from different drive magazines.
• Physical disks with fewer used chunklets should be used before physical disks with more used
chunklets.
• Chunklets in the same row should be from different physical disks. In other words, a physical
disk should not appear twice in the same row.
• Chunklets should belong to a disk that is connected through the primary path to the LD owner
node.
• The system should use as many physical disks as possible.
• The load on all physical disks should be balanced.
• The system should use the largest possible row size.
NOTE: The system may round up when creating LDs to support virtual volumes and CPGs, resulting
in a discrepancy between the user-specified size or growth increment and the actual space allocated
to LDs created by the system. For more information, see “LD Size and RAID Types” (page 40).
Volume Types Associated with CPGs
Depending on the products and features licensed for use on the system, after creating a CPG you
can create two types of base volumes that draw from the CPG's LD pool—TPVVs and FPVVs. These
two volume types draw from the pool in different ways. For information about TPVVs, see
“Thinly-provisioned Virtual Volumes” (page 9). For information about FPVVs, see “Fully-provisioned
Virtual Volumes” (page 8).
System Guidelines for Creating CPGs 43