topic Re: MSA i/o analysis in Disk Enclosures

MSA i/o analysis

Jake M_1 — Thu, 09 Apr 2009 12:32:21 GMT

Hi,

I am finding that disk i/o is not quite what i expected from my disk arrays and i am after doing some I/O analysis and wonder where to start...?

Server Setup
-HP DL580 G5
-12GB RAM
-2 x Intel Xeon E7330 Quad Core @ 2.4ghz
-3 x HP MSA 30 (Dual Bus)
-- 42 x 300GB U320 SCSI @ 10K RPM (14 per MSA)
-2 x 6400 RAID Controllers
-MS Windows Server 2003 R2 Standard x64

I have a number of logical disks presented from the MSA's to windows (all RAID 5)

Question #1)
I was wondering how the logical disks are stored on the MSA's.
Is I/O optimised by spreading the logical disk across multiple disk spindles or does ACU simply start at the beginning of disk #1 and move across gradually until all disks are full?
Thus if you are only using 50% then the second half of your disks are empty and the first half are full?

Question #2)
I know how to analyse physical / logical disk performance using perfmon from within windows, but it doesnt really break down what is actually happening on the MSAs.
I really could do with some way of analysing the MSA I/O and possibly the individual disk I/O to give me an idea of where the bottle neck is.
Does anyone have an idea where i could start?

Any help is greatly appreciated.

Thanks

Re: MSA i/o analysis

Torsten. — Thu, 09 Apr 2009 12:36:19 GMT

just my 2 cents:

1) it's a RAID5, so the data is across all disks.

2) it's a hardware array, so the OS knows nothing about disks behind.

Re: MSA i/o analysis

Jake M_1 — Thu, 09 Apr 2009 12:43:31 GMT

Hi,
Thanks for your reply, its appreciated.

I know that with it being a RAID 5 array it would be across more than one disk but are you certain that any logical drive is striped across them all? That would be perfect for me but it just doesnt seem to perform as if thats the case...

I figured that windows knows nothing about the physical disks but i thought that perhaps there would be some utility that could monitor the array its self, perhaps something from HP for the 6400 RAID controller?

Any ideas what the maximum theoretical throughput would be for an MSA 30 (Dual Bus) with 14 x 300 GB 10K disks as above? Maybe theres some counts & calculations i can do to see whats going on...

Thanks again,

Re: MSA i/o analysis

Torsten. — Thu, 09 Apr 2009 12:55:34 GMT

I have a document

RAID Technology Overview
J6369-90050

This may help you, but I don't have a link at the moment nor I can attach it.

Maybe you are able to find it.

Re: MSA i/o analysis

Sivakumar MJ._1 — Thu, 09 Apr 2009 13:31:28 GMT

Check the forums, related one

http://forums11.itrc.hp.com/service/forums/questionanswer.do?threadId=1216005

http://forums11.itrc.hp.com/service/forums/questionanswer.do?threadId=1161562