HP 3PAR Policy Manager Software - Manual (Page 40)

A.2
3PAR Policy Advisor User’s Guide
Can you give me an overview of how Policy Advisor analyzes virtual volumes that
provision space from Common Provisioning Groups (CPG)?
■ When a virtual volume is created or grown, one or more groups of LDs are associated with
the CPG. The Policy Advisor performs the following analysis tasks on these groups of LDs:
◆ Analyzes the current group of LDs for the number of disks used.
◆ Analyzes the number of disks that would be used by a similarly sized LD group with the
same characteristics as the original group if it were created on the system at this time.
◆ If the LD group created at this time would improve the layout, all virtual volumes with
user space in this LD group will be considered for tuning.
■ All virtual volumes identified in the final step will have simulated, or dry-run, tuning
operations run against them to verify that the suggested tuning operations will work.
Why can't I get tuning suggestions for some virtual volumes?
There are a number of conditions under which virtual volumes are excluded from analysis:
■ Virtual volumes with active or scheduled tuning operations are excluded.
■ Virtual volumes that provision space from different CPGs cannot be tuned automatically.
For more information, see Virtual Volumes Created from Different Common Provisioning
Groups on page 4.14.
■ Virtual volumes that provision space directly from LDs with different RAID types are
excluded. Policy Advisor does not have enough information to determine which RAID type
the virtual volume should use for the tuning operation. Logical disks with different RAID
types are highlighted in the virtual volume report as a skip reason.
Why are virtual volumes that provision space directly from LDs with mixed RAID type
LDs skipped, while virtual volumes that provision space from CPGs with mixed RAID
type LDs are considered for tuning?
■ For virtual volumes that provision space directly from LDs with mixed RAID type LDs,
insufficient information about LD RAID types is available to the Policy Advisor. For virtual
volumes that provision space from CPGs with mixed RAID type LDs, the CPG characteristics
like RAID type and set size are used to tune the target virtual volumes that provision space
from CPGs.