Auto lun statistics – HP XP Auto LUN Software User Manual

Page 37

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Auto LUN XP user guide for the XP1024/XP128

37

2

Auto LUN/Performance Control Base Monitor for the

XP1024/XP128

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.

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