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Need your expertise on SAN Drives performance/speed

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Need your expertise on SAN Drives performance/speed

Hi folks, this is my first post on HP SAN forum. We have an EVA4000 running at 2gbps fibre channel.

I used HD Tach to benchmark the two Vdisks listed below which were presented to a physical machine with the following config:

HP DL360
1x dual core Xeon 3.4GHz
4gb RAM
Windows 2003 Server

My concern is with the average read and burst speeds we’re seeing. They seem awfully slow as I get better on my local desktop!

Are these results normal? Could someone help me to verify?

I was expecting way better performance from my SAN.

Test Configuration:

Vdisk 1
260gb RAID 5
Disk group: 16x 500gb FATA 7200 rpm drives

Vdisk 2
300gb RAID 5
Disk group: 32x 146gb FC 10k rpm drives

After running the tests multiple times, the results of the two tests were very similar.

Vdisk 1
Random access: 14ms
Average read: 40 MB/s
Burst Speed: 107.4MB/s

Vdisk 2
Random access: 7.6ms
Average read: 41.7MB/s
Burst Speed: 107.8 MB/s

Many thanks.
Uwe Zessin
Honored Contributor

Re: Need your expertise on SAN Drives performance/speed

Many storage arrays are designed for performing better at many I/O operations per second, not MegaByte per second. I don't know the I/O pattern of this "HD tach", but I can easily show very different MB/s throughput just by changing the block size between 32 KBytes and 512 Bytes. Or change, if possible, the number of outstanding I/Os on your test program.

I've been at a customer who was running an old "DOS-style" application (Navision 'classic' running under cmd.exe). He wanted to compare his new EVA with the old system and ran a predefined task to alter some data. Well, the performance was not better - because it is a single-threaded task. I asked him to run some more tasks and we could see that the EVA's I/O throughput was growing with each additional task.
Víctor Cespón
Honored Contributor

Re: Need your expertise on SAN Drives performance/speed

It depends a lot on how the softare does the test.

I see very strange that you get 40 MB/s from both disk groups, since one has 16 disks and another 32. Also, 500 GB FATA disks are the slower ones, slower than al other FATA, don't expect too much from them.

You could be limited by the HBA queue depth or some parameter in Windows. Also, if you have more than one HBA try enabling load balancing in MPIO.

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