How to interpret what I am seeing in Performance Detail.

We have an application that has a MetaLUN.

This MetaLUN is spread across 10 RAID 5 groups (4+1). The DB guys ask if we are seeing any performance issues with their LUN.

I open Performance view in Analyzer and select the LUN and the disks. When I look at response time I have a spike that reached 16million.. yes MILLION milliseconds for the LUN. All the disks (All 50 of them) are less than 40ms response time.

So my question is... Why would I see such a large response time viewing the MetaLUN and see good response times from the disks which make up that MetaLUN?

Thanks!

Responses(4)

DGM3

238 Posts

0

February 18th, 2008 10:00

This question comes up from time-to-time and is generally associated with a period during which IO loading on the Storage Processor is very low, thus creating opportunity for some of the derived statistics to yield exceptional values. Was the SP lightly loaded during the time the spike was observed? Also, what revision of storage system software (Flare) is being used, and what type of array is it (e.g. CX700)?

A prior thread that briefly discussed the same, is here;
http://forums.emc.com/forums/thread.jspa?threadID=58987

Regards,
DGM

DHoffman2

306 Posts

0

February 18th, 2008 11:00

Crud, I didnt think to give more specifics.

CX3-80 FLARE Code 24 Rev. 11

The SP does indicate a ver low response time, except for some peaks that go as high as 224ms. Good follow up question.

I'll review the link you sent DGM and see if that shed any additional light.

DGM3

238 Posts

1

February 18th, 2008 11:00

Some enhancements in this area have already been implemented in Flare, particularly in Release 26 software. Are you perhaps already planning to upgrade to the latest patch level of R24, and/or move to R26, on the array in question?

If you may want to open a support case (if logs showing the event in question can be available for review) the support team could likely offer further comment. If you do open a case, please advise back here what the SR number assigned is.

Regards,
DGM

DHoffman2

306 Posts

0

February 18th, 2008 11:00

DGM,

This is what I am seeing, however do you know if EMC plans on resolving this "false positive"?

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How to interpret what I am seeing in Performance Detail.