DSS FC write problems

[hughesmikea]

Hi,

I have been testing various block and frame size settings to see what performs the best and I have run into write performance issues.

The SetupDSS 3511 with a Qlogic QLE2462
XenServer 5 (Update 3) with a Qlogic QLE2462
Qlogic 5600 switch in between

I created a 10GB volume on DSS for each block size (512, 1024, 2048 and 4096). I attached each as a Storage Resource to XenServer.

One at a time I created a 5GB partition and attached them to a Win2k3 VM server. The only one Win2k3 could see properly was with the 512 block size. All the others did not show the proper size partition and would not initialize. I also changed the FC frame size settings on both ends (512, 1024, 2048), but it did not make a difference.

I then proceeded to perform READ tests. The best numbers were with a 512 frame size. Then I started WRITE testing and this is where my trouble began. I would get a quick burst, then the test would lockup.

The next thing I did was to do a simple file copy. I copied 2GB of data to the partition. The copy would go in short bursts and take forever to complete.

For comparison I attached the XenServer to a volume on our SANMelody SAN and did the same set of test. While the performance was less then what I was getting with DSS, the READ and WRITE operations worked perfectly.

So my conclusion, being that I am using the exact same software and hardware for testing, is there is something wrong on the DSS side.

One other note -- I found that if I create a FC volume on DSS and attach it to the XenServer, then detach it from the XenServer and change something on DSS, like delete and created another volume, I have to reboot both xen and DSS for xen to see the updated volumes correctly.

Any suggestions on how to fix the WRITE issue??
Mike

[Robotbeat]

Are you using the "default" blocksize when you format the drives as ntfs? When I tested FC volumes with different blocksizes set on the DSS interface, I manually set the blocksize in windows as I was formatting them as ntfs. This was also with windows 2003. Have you done anything like that?

[hughesmikea]

I did format with default. Just now talking with Todd, I reformated with 512 and 4096 and got the same bursty respone on writes.

[symm]

HI hughesmikea

Your Qlogic 5600 switch settings are they set to auto?
If so set them manually.

[hughesmikea]

I changed the switch ports for DSS from auto negotiate to 4GB. No difference. I/O guard is set to auto.

I did not change the ports for Xen, because I do not have this issues from Xen to SANmelody on the same switches.

thanks
mike

[symm]

Hi hughesmikea

What RAID level are you using?
Can you try enabling cache and read ahead on your RAID controller.
how much RAM do you have ?
Is it locking up or is the write fast in the beggining and then slowing down?