topic Average Disk Queue length on SAN in HPE EVA Storage

Average Disk Queue length on SAN

Christian Bieletzki — Wed, 11 May 2005 10:34:24 GMT

I have a SAN based on a MSA 1000 dual channel controller 256 MB cache and 2 servers attached.
An exange server is attached to the internal storage cage of the MSA 1000 configured as follows:

14 x 72 GB disks 10.000 rpm
50% read 50% write cache
16KB stripe size (default)
RAID ADG

The Avg. Disk Queue Length is 24,696 which (my opinion) is significantly high.

I know from the past that this walue should never be constantly higher than 2.

Is there any other awareness about this value in SAN environments (respective the MSA 1000).
Does someone has a similar system to measure this parameter against?

Any comments would be useful.

Kind regards
Christian

Re: Average Disk Queue length on SAN

Beer Grill — Thu, 12 May 2005 02:05:52 GMT

Have you used Diskpar or Diskpart to align your partitions with your OS.Aligning your partitions could boost your performance by 20% according to some docs I've read on the web.This misalignment is something I've only lately stumbled upon when investigating poor EVA5000 disk performance.
Its never been mentioned in any training I've done.There is an HP whitepaper available on this which is referenced in the attachment

Re: Average Disk Queue length on SAN

Tv_3 — Thu, 12 May 2005 03:40:50 GMT

Avg Disk Queue length is to high, the design consideration from microsoft are that these values never should go over the THREE.

Check you controller driver/firmware versions againt the latest you'll find on the website.

Greetzzz

Re: Average Disk Queue length on SAN

Uwe Zessin — Thu, 12 May 2005 03:53:45 GMT

http://h20000.www2.hp.com/bizsupport/TechSupport/Document.jsp?objectID=PSD_OI040301_CW02&printver=true