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disk queue length

i have a hp raid 10 array with 6 disks, what is the threshold for disk queue length? is it 2 per disk? so in my case it would 12?
Kylo Ren
Kylo Ren
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If the average disk queue length is greater than twice the number of disks in the volume/array then the storage is the bottleneck, so in your case yes 12.

You could certainly look into the average read and average write indications separately to get further information.
David Johnson, CD, MVPOwnerCommented:
@gmbaxter: Yes that is the theory.. Whether or not it affects the user experience is another question. On my drive E (6 Drives in a Storage Space) the current disk queue is 58 (I am pausing a Vmware workstation), yet it doesn't impact my other running applications..
Yes it does depend on the application in that respect. In a 16 disk array running user home folders I've seen queues of 35 severely affecting performance.

The main thing to do is to analyse the issue, if you view the application as a user at peak times and you think there is a problem, then look into where the problem originates from. If however things are running smoothly, then don't just throw money at a san/array just because a graph says so.
Here is a TechNet article for bottleneck calculations
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