This article indicates how to monitor performance on storage devices with PowerPath.

The PowerPath 5.2 above release introduces the command to display performance metrics for storage devices and busses. Collection of data starts once the powermt set perfmon= command is set. Once setting the perfmon command to "on" initialize the performance monitoring counter and measurements. In addition to powermt set perfmon, there are two more commands that can be used to collect enhanced performance information:

• powermt display perf dev
• powermt display perf bus

The output of these commands provide:

• Read, Write, and Total Throughput
• Read, Write and All Average Response Time
• Read, Write peer I/O size
• Queued-I/Os
• Latency Distribution
• Retry delta
• Error delta

Following table shows the detail PowerPath version supporting the command:

             

Command	AIX	HP-UX	Linux	Solaris	Windows
powermt display perf dev	5.7	5.2	5.7	5.5	5.7
powermt display perf bus	5.7	5.2	5.7	5.5	5.7

powermt display perf dev

powermt display perf dev displays storage device performance metrics for all logical devices. The output has one line per path. There is a table for each type of storage device. The storage device count above each table includes the type of storage device to which that table applies. If there is no data for the device or if there is no device specified, the following error message is thrown: “Device(s) not found”.

If performance monitoring has just been turned on and continuous is specified, then the first output will wait until the first interval has completed, and subsequent output will also wait the interval time.

The following output for the powermt display perf dev command shows performance metrics of a CLARiiON storage system.

# powermt display perf dev=all verbose

Timestamp = 22:25:54 UTC, 12 Mar 2012

Sample Interval = 300

Pseudo name=emcpower32a

state=alive; policy=SymmOpt; queued-IOs=10

                     KB<=4K 4K 128K   All

Read bytes/s          4.50M   3.25M      13.1M       -     20.8M

Write bytes/s         4.50M   3.26M      13.1M       -     20.8M

Total bytes/s                                              41.6M

Read Avg Response ms   1.03   0.985       1.01       -      1.02

Write Avg Response ms  1.05   0.989       1.02       -      1.04

All Avg Response ms                                         1.03

Read IOs/s             2.80K    396        796       -      3.99K

Write IOs/s            2.79K    397        798       -      3.99K

Total IOs/s                                                 7.98K

================================================================================

--------------- Host --------------- Latency -------------- Retry Error

### HW Path I/O Paths            Reads---Writes             delta delta

================================================================================

3073 pci@0/pci@0/pci@8/pci@0/pci@1/QLGC,qlc@0,1/fp@0,0 c5t50000972081A4D95d384s0

                       Low (ms)   0.139  0.197                0     0

                      High (ms)    34.5   34.7

                 Lat <= 1ms (#)   76004  71588

          1ms < Lat <= 10ms (#)   73418  76847

        10ms < Lat <= 100ms (#)      25     35

                Lat > 100ms (#)       0      0

powermt display perf bus

powermt display perf bus displays path performance metrics for each buses. If performance monitoring has just been turned on and continuous is specified, then the first output will wait until the first interval has completed and the subsequent output will also wait the interval time. The summary display information does not list any arrays if there are no devices for an array type.If there is no device specified, the following error message is thrown: ” Device(s) not found”

The following output for the powermt display perf bus command shows performance metrics of a Symmetrix storage system:

# powermt display perf bus verbose

Timestamp = 14:25:54 UTC, 13 Mar 2012

Sample Interval = 300

Symmetrix logical device count=418

==============================================================================

----- Host Bus Adapters --------- ------ Storage System ----- Retry Error

### HW Path                       ID              Interface   delta delta

==============================================================================

3072 pci@0/pci@0/pci@8/pci@0/pci@1/QLGC,qlc@0/fp@0,0

000192601683 FA 6gB 0 0

   Latency----Reads--Writes

    Low (ms) 0.138 0.196

   High (ms) 34.6 34.6

    Lat <= 1ms (#) 75876 71571

1ms < Lat <= 10ms (#) 72599 77647

    10ms < Lat <= 100ms (#) 39 39

   Lat > 100ms (#) 0 0

3072 pci@0/pci@0/pci@8/pci@0/pci@1/QLGC,qlc@0/fp@0,0

000192601683 FA 5gB 0 0

  Latency----Reads--Writes

   Low (ms) 0.138 0.197

  High (ms) 38.4 30.6

   Lat <= 1ms (#) 72033 69174

1ms < Lat <= 10ms (#) 75792 78296

    10ms < Lat <= 100ms (#) 26 32

  Lat > 100ms (#) 0 0

3073 pci@0/pci@0/pci@8/pci@0/pci@1/QLGC,qlc@0,1/fp@0,0

000192601683 FA 6gB 0 0

  Latency----Reads--Writes

   Low (ms) 0.139 0.192

  High (ms) 34.5 34.7

   Lat <= 1ms (#) 75561 71178

1ms < Lat <= 10ms (#) 73703 76272

    10ms < Lat <= 100ms (#) 40 55

  Lat > 100ms (#) 0 0

For more information on these CLI commands, refer to the EMC PowerPath Family CLI and System Messages Reference Guide,

Author: Fenglin Li

iEMC APJ

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