HP XP Array Manager Software - Manual (Page 17)

A RAID-5 parity group consists of four or eight HDDs. One of these HDDs is used as a parity disk.
• RAID-6 parity group
A RAID-6 parity group consists of eight HDDs. Two of these HDDs are used as a parity disk.
If the monitor data shows overall high parity group usage, you should consider installing additional
HDDs and using XP Auto LUN to migrate the high-usage volumes to the new parity groups. If the
monitor data shows that parity group usage is not balanced, you can use XP Auto LUN to migrate
volumes from high-usage parity groups to low-usage parity groups.
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 about parity groups, see “ Viewing Usage Statistics about
Parity Groups ” on page 61.
Volume Usage Statistics
Performance Monitor displays the average and maximum usage, including sequential and random
access, of each volume (LDEV) in a parity group. The volume usage is the time in use (sequential and
random access) of the physical drives of each LDEV, averaged by the number of physical drives in
the parity group.
If the monitor data shows overall high volume usage, you should consider installing additional hardware
(for example, HDDs, DKAs, cache). If the monitor data shows that volume usage is not balanced, you
can use XP Auto LUN to migrate high-usage volumes to higher HDD classes and/or to lower-usage
parity groups. The volume usage data can also be used to analyze the access characteristics of
volumes and determine the appropriate RAID level and/or HDD type for the volumes.
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 about volumes, see “ Viewing Usage Statistics about Volumes
in Parity Groups ” on page 63.
External Volume Group Usage Statistics
If the storage system is connected to an external storage system by HP StorageWorks XP External
Storage Software, Performance Monitor can also monitor the usage conditions on external hard disk
drives.
When you use XP External Storage to map the volumes in the external storage system as volumes in
the storage system, the mapped volumes in the external storage system are called external volumes.
These external volumes are registered in groups by XP External Storage. Performance Monitor can
monitor the usage conditions for external volume groups.
An external volume group is just a group for managing external volumes. Unlike a parity group, it
does not contain any parity information. However, some windows of Performance Monitor treat
external volume groups same as parity groups.
The information that can be monitored about an external volume group differs from that of a usual
parity group. For details on how to view usage conditions about external volume groups, see “
Viewing
Usage Statistics about External Volume Groups ” on page 66.
XP24000/XP20000 Performance Monitor User Guide 17