3PAR InForm® OS 2.2.4 Concepts Guide (320-200085 Rev B, March 2009)

10.7
Volume Types Associated with CPGs
InForm OS Version 2.2.4 3PAR InForm OS Concepts Guide
In addition, volumes that draw from a CPG can only use the space available to that CPG based
on the CPG's logical disk parameters. For example, if you create a CPG that only uses logical
disks that belong to controller node 0, when the virtual volumes that draw from a CPG have
filled up all space available to that CPG based on it's logical disk parameters, the following will
happen:
■ New writes to any thinly provisioned virtual volumes (TPVVs) 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’s growth limit, the system generates
additional alerts to notify you that all logical capacity for the CPG has been consumed.
10.3 Volume Types Associated with CPGs
Depending on the products and features licensed for use on the system, after creating a CPG
you can create up to two types of base volumes that draw from the CPG's logical disk pool:
thinly provisioned virtual volumes (TPVVs) and commonly provisioned virtual volumes (CPVVs).
These two volume types draw from the pool in different ways. For information about TPVVs,
see Thinly Provisioned Virtual Volumes on page 8.11. For information about CPVVs, see
Commonly Provisioned Virtual Volumes on page 8.15.
CAUTION: Use caution in planning CPGs. The system does not prevent you from
setting CPG growth warnings or growth limits that exceed the amount of
currently available storage on a system. When volumes associated with a CPG use
all space available to that CPG, any new writes to TPVVs associated with the CPG
will fail and/or snapshot volumes associated with the CPG may become invalid
(stale). Under this condition, some host applications do not handle write failures
gracefully and may produce unexpected failures.