HP-UX Reference (11i v1 05/09) - 1M System Administration Commands A-M (vol 3)

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arraydsp(1M) arraydsp(1M)

Display information for all LUNs on the disk array identiﬁed by alias

AUTORAID4:

arraydsp -l AUTORAID4

Display information for all disks installed in disk array serial number

00786b5c0000 :

arraydsp -d 00786b5c0000

List the serial numbers of all of the disk arrays recognized by the host:

arraydsp -i

Display performance recommendations for disk array serial number

00786b5c0000 . Analyze perfor-

mance for the time period from 8:00 AM to 5:00 PM (1700) on March 15.

arraydsp -r 03150800 03151700 00786b5c0000

Display performance metrics for disk array serial number

00786b5c0000 . Analyze performance for the

time period from 1200 PM to 6:00 PM (1800) on April 6. Use a display interval of 30 minutes.

arraydsp -m 04061200 04061800 2 00786b5c0000

PERFORMANCE METRICS

The following information describes the various performance metrics returned by the -m option.

Metric Description

Drive Diff Values (Typical/Limit): 0-1/>1

Indicates if the disks are properly distributed across the internal SCSI channels. If the

disks are not installed properly, one of the SCSI channels may be handling more than

its share of activity, reducing performance. Redistributing the disks will solve this prob-

lem.

Relocate Blocks Values (Typical/Limit): 0.008/>0.07

Indicates how much data is being moved between RAID 0/1 and RAID 5. If too much

data is being transferred between RAID 0/1 and RAID 5, performance declines.

Working Set Values (Typical/Limit): 1/>1.1

Indicates the ratio of the write working set to the amount of RAID 0/1 space available.

To maintain performance, the amount of RAID 0/1 space should equal or exceed the

write working set (a value of 1 or less). A value greater than 1 indicates that the work-

ing set is larger than the available RAID 0/1 space. In this case, the disk array must ser-

vice writes from RAID 5 space, which degrades performance.

Cache Utilization Values (Typical/Limit): 0.1/0.2

Indicates how efﬁciently the write cache on the disk array controller is being utilized. If

the write cache is consistently full, too many commands begin stacking up in the cache

queue, resulting in decreased performance.

Disk Queue Values (Typical/Limit): 2-4/>=10 (per disk)

Indicates the average number of transactions on all disk drives waiting in the internal

disk SCSI queues. Too many commands in the queues decrease performance.

Concurrency Values (Typical/Limit): >= drive count/< drive count

Indicates the number of internal simultaneous disk accesses the disk array is making.

The disk array achieves optimum performance when it is accessing multiple disks at the

same time, so some concurrency is desirable. Too low a value indicates that the host is

not requesting enough concurrent I/Os to keep the disk array busy.

Cache Queue Values (Typical/Limit): 0.05/>=0.32

Indicates the number of commands in the cache queue. An excessive number may reﬂect

address conﬂicts in host I/Os, caused by repeated access to the same block(s) of data.

Host Queue Values (Typical/Limit): 0/>32

Indicates the number of host commands waiting in the host queue. A problem here typi-

cally reﬂects another bottleneck further along in the controller data path. For example,

if the cache queue is full, commands will stack up in the host queue waiting for the

Section 1M−−52 Hewlett-Packard Company − 3 − HP-UX 11i Version 1: September 2005