Assigning Volume Group Ownership; Selecting A Raid Level - HP Surestore Disk Array 12h - And FC60 Service Manual

Assigning Volume Group Ownership

When a volume group is bound, you must identify which disk array controller (A or B)
owns the volume group. The controller that is assigned ownership serves as the primary
I/O path to the volume group. The other controller serves as the secondary or alternate
path to the volume group. If there is a failure in the primary I/O path and alternate links are
configured, ownership of the volume group automatically switches to the alternate path,
maintaining access to all data on the volume group.
When assigning volume group ownership, consider the following:
•
To ensure optimum performance, volume group ownership should be balanced between
controllers. This ensures that one controller is not overloaded with I/O requests, while
the other is idle.
•
Controller ownership can be changed on an existing volume group without impacting
its operation. If you find that there is an imbalance between I/O path loads, you can
change the ownership of one or more volume groups to solve the problem.

Selecting a RAID Level

The RAID level you select for each volume group determines the method used to store data
on the disks. The RAID level assigned to the volume group can be changed dynamically if it
is determined that a different RAID level would be more appropriate.
With the exception of RAID 0, all RAID levels supported by the disk array provide
protection against disk failure. However, there are differences in performance and storage
efficiency between RAID levels. For more information on RAID levels and their
comparative operating characteristics, see
The two factors that will influence the RAID level you select are performance and storage
efficiency.
•
Performance - The performance characteristics differ for each RAID level. The types
of applications you are running and the I/O activity associated with them should
influence the RAID level you select for a volume group. The performance
characteristics for each RAID level are summarized in
page 55.
"RAID Technology" on page
"RAID Level Comparisons" on
Managing Disk Array Capacity
45.
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