Stripe Size Greater than 32k for SAP/Oracle/HP-UX/EMC

[Cossy Cosmas]

Need some advice please.

I am currently running a variety of SAP systems(V3&4) on a hup-ux 11 platform with Oracle 8 providing the back end rdbms. We use an EMC disk array with a 32k stripe size and all is working pretty well.

This weekend, however, we plan to upgrade our EMC array to an 8430 and I have been advised by a friend that there are significant performance improvements to be had by increasing the stripe size to 64k.

Naturally, the idea of any performance benefits is of interest to me but would like some reassurance from anyone who has done this for themselves. This is not the sort of change that we can easily back-out from if it has a detrimental effect on performance!!

Also, please don't point me to the EMC performance papers as they are years old and do not mention 64k stripe sizes.

Any feedback greatly appreciated.

Regards,

Cossy

[Tim Malnati]

I doubt you will see any improvement using 64k stripes, rather I think that you may see your throughput degraded instead. The only situation that may be different is if the EMC has an abundance of installed memory; to the extent where most i/o is satisfied by cache. I would be very reluctant to change your current layout until your friend can quantify his situation with some form of benchmark. Even then you need to carefully consider the specifics of his hardware configuration to determine why 64k blocks allowed software performance to improve.

[Naveen Shetty]

There should be some improvement. Refer
to Oracle/EMC/Veritas white paper on SAME.
I have FC60 with strip unit 256KB with strip width set to 2MB for each raid group.It is
performing better than my earlier NAS where
the strip unit was 4KB.

Regards
Yasin
yasin@apaints.com

[Pedro Sousa]

I agree with Tim,
normally you have to pu stripe with smaller blocks to improve it's performance. Check Your Oracle block size and may be it's a good idea to put them equal.
I spoke with a guy from EMC Spain, and he told me that, for better performance, normally it was better to stripe with 16kb.

I advise you to check if the transactions of your db are very big, or if they have ramdom size.
If it matches the first case, I think you should try 64kb, if not maybe 16kb.

good luck