Disk Tests: Valid for iSCSI SAN Array?

[dobrien]

We got a new Dell MD3200i iSCSI SAN disk array last month and have been getting abysmal data rates when copying files off the disk array. I ran the Sequential Read Test on the RAID 1 local C-drive, and get great read times of ~150 MB/sec. When I run the read test on the disk array in the MD3200i, I get awful read times from 3.47 MB/sec to as "high" as 6.7 MB/sec. I've run the "very large" test and times are basically the same as the short test.

My question is does anyone know if Performance Test produces a valid result for an iSCSI SAN disk array? One disk group is RAID 1+0, the other is RAID 1. The times are about the same for either. Times for non-SAN disks seem normal.

Edited to add: This is a Windows 2008R2 server.

[David (PassMark)]

There is no reason the disk test shouldn't work on a SAN. I think the only possible issue might be results that are too high as a result of a large amount of cache on the SAN. I couldn't see any mention of cache for the Dell MD3200i, so I assume it doesn't have much if any.

As you get slow transfer speeds using PerformanceTest and with doing a normal file copy, it would seem to PerformanceTest is just confirming what you already knew.

iSCSI transfers SCSI commands and data over TCP/IP. So there are lots of potential areas for a bottle neck or misconfiguration.

[dobrien]

Thanks for your help.

[Solema]

dobrien,
I found this forum thread through Google searching. I'm having the exact same problems with excruciatingly slow read speeds on my MD3200i SAN. Have you fixed the speed issue? And if so, how did you fix it? I've spent the last week on the phone with Dell and they have no idea how to fix it!

Thanks,
Nick

[David (PassMark)]

Did you look at the latency and bandwidth of the network link (without using SAN)

[Solema]

Yes, the latency of the network is practically nothing. It's definitely not that.

[Gomer321]

You posted a really intersting rundowm cause it helped me a lot...Well-done!!!