HP StorageWorks XP Remote Web Console Software - Manual (Page 37)

Auto LUN XP user guide for the XP128/XP1024 37
2 Auto LUN/Performance Control Base Monitor for the
XP128/XP1024
Auto LUN statistics
Disk arrays automatically collect statistics twice a day (in the morning and afternoon). Auto LUN monitors
disk arrays and obtains usage statistics about resources such as front-end and back-end processors, hard
disk drives, and logical volumes every 15 minutes.
Auto LUN displays statistics collected for the last three months. Statistics over three months old are
discarded.
You can specify a time period and view a graph illustrating how usage rates change within that time
period. You can also view average and maximum usage rates.
You can analyze information displayed on the pane and identify overloaded resources. If necessary, take
load-balancing measures to improve system performance.
Auto LUN displays the following types of information:
• Usage statistics about parity groups. If data shows overall high parity group usage, consider installing
additional HDDs and using Auto LUN to migrate high-usage volumes to the new parity groups. If
monitor data shows unbalanced parity group usage, use Auto LUN to migrate volumes from high-usage
parity groups to low-usage parity groups.
• Usage statistics about logical volumes. Auto LUN displays average and maximum usage, including
sequential and random access, for each LDEV in a parity group. Logical volume usage is the time in
use (sequential and random access) of the physical drives of each LDEV, averaged by number of
physical drives in the parity group.
If data shows overall high logical volume usage, consider installing additional hardware (for example,
HDDs, DKAs, or cache). If monitor data shows unbalanced volume usage, use Auto LUN to migrate
high-usage volumes to higher HDD classes and/or lower-usage parity groups. You can also use logical
volume usage data to analyze access characteristics of volumes and determine appropriate RAID level
and/or HDD type for the volumes.
• Usage statistics about channel adapters and channel processors. Channel adapters (CHAs) process
host commands and control data transfer between hosts and cache. A channel adapter contains
multiple channel processors (CHPs), which process host commands and control data transfer.
If data shows overall high CHA usage, consider installing additional CHAs. If data shows unbalanced
CHP usage, consider moving some devices defined on overloaded ports to ports with lower-usage
CHPs to balance front-end usage.
• Usage statistics about disk adapters and disk processors. Disk adapters (DKAs) control data transfer
between cache and disk devices. A disk adapter contains multiple disk processors (DKPs), which
control data transfer.
If data shows overall high DKP usage, consider installing additional HDDs and/or DKAs and using
Auto LUN to migrate high-write-usage volumes (especially sequential writes) to the new parity groups. If
data shows unbalanced DKP usage, use Auto LUN to migrate logical volumes from high-usage parity
groups to low-usage parity groups.
Auto LUN cannot estimate DKP usage. Use Auto LUN migration only for obvious cases of high or
unbalanced DKP usage. Auto LUN migration might not improve performance if DKP usage values vary
only slightly or if overall DRR usage values are relatively high.
• Usage statistics about data recovery and reconstruction processors. Data recovery and reconstruction
processors (DRRs) are microprocessors located on DKAs that generate parity data for RAID-5 parity
groups. DRRs use “old data + new data + old parity” to generate new parity.
If data shows overall high DRR usage, this might indicate a high write penalty. Consult your
HP representative about high write penalty conditions. If data shows unbalanced DRR usage, consider
using Auto LUN to relocate volumes to balance DRR usage within the disk array.