HP XP Array Manager Software - Manual (Page 21)

Migrating Volumes in an XP24000 Disk Array Disk Processor Disk Adapter Cluster
Migrate volumes from parity groups with the following
IDs to another parity group:
10-X
18-X
DKPF4-2WL
DKPF5-2WL
DKPF6-2WL
DKPF7-2WL
DKA-2WL 2
NOTE:
The letter X is a placeholder for numerical values. For example, parity group 1-X indicates parity
groups such as 1-1 and 1-2.
XP Auto LUN cannot estimate DKP usage, and may not provide any performance improvement for
cases in which DKP usage values vary only slightly, or for cases in which overall DRR usage values
are relatively high. XP Auto LUN is designed for use with obvious cases of high or unbalanced DKP
usage. For more information on using XP Auto LUN, see the HP StorageWorks XP24000/XP20000
Auto LUN Software User Guide.
DRR Processor Usage Statistics
A data recovery and reconstruction processor (DRR) is a microprocessor (located on the DKAs) that
is used to generate parity data for RAID-5 or RAID-6 parity groups. The DRR uses the formula old data
+ new data + old parity to generate new parity.
If the monitor data shows high DRR usage overall, this can indicate high write penalty condition.
Please consult your HP representative about high write penalty conditions. If the monitor data shows
that DRR usage is not balanced, you should consider relocating volumes using XP Auto LUN to balance
DRR usage within the storage system.
For more information on using XP Auto LUN, see the HP StorageWorks XP24000/XP20000 Auto
LUN Software User Guide.
For details on how to view usage statistics on DRRs, see “ Viewing Usage Statistics about Data Recovery
and Reconstruction Processors (DRRs) ” on page 71.
Write Pending Rate and Cache Memory Usage Statistics
The write pending rate indicates the ratio of write-pending data to the cache memory capacity. The
Auto LUN window displays the average and the maximum write pending rate for the specified period
of time. When you display monitoring results in a short range, the window also displays the average
and the maximum usage statistics about the cache memory for the specified period of time. In addition,
the window can display a graph that indicates how the write pending rate or the usage statistics of
the cache memory changed within that period.
NOTE:
The data written to the Cache Residency cache area is not included in the write pending rate field.
For details on how to view the write pending rate and the usage statistics about the cache memory,
see “
Viewing Write Pending and Cache Memory Usage Statistics ” on page 72.
XP24000/XP20000 Performance Monitor User Guide 21