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EVA VDISK presented to Windows Server

Aspi Jasoomani
Occasional Visitor

EVA VDISK presented to Windows Server

When an EVA virtual disk is presented to a windows server what should the 'Average Disk Queue Length' counter for this Vdisk on the Window server show through Perfmon. Should it be 'less than 2' or should it be "less than 2 X Number of Spindles in Disk Group" that this VDISK is carved out from. Example if the Disk Group in the EVA consists of 80 spindles should the 'Average Disk Queue Length' counter in Perfmon on the windows server be less than 160?

All help is appreciated. Thanks.
2 REPLIES
Ivan Ferreira
Honored Contributor

Re: EVA VDISK presented to Windows Server

According to microsoft:

On multiple disk RAID arrays, the average disk queue length per array should not exceed the number of physical disks per array.

See:

http://www.microsoft.com/technet/prodtechnol/sscomm/reskit/rkcapmit.mspx

You should use also evaperf and get a baseline for your system that you can use for future troubleshooting.
Por que hacerlo dificil si es posible hacerlo facil? - Why do it the hard way, when you can do it the easy way?
Aspi Jasoomani
Occasional Visitor

Re: EVA VDISK presented to Windows Server

Ivan, Thanks for your reply. However I am not sure if that's the case when the server is presented with a virtual disk through the EVA.
The reason I say this is that when I check the 'Average Disk Queue Length' for a number of different VDISKS presented to various Windows servers they all show me a count of "less than 2" in Perfmon on the server; and all these virtual disks are carved out of disk groups consisting of 80 to 120 spindles. So if it was that the 'Average Disk Queue Length' should be less than "2 X the number of spindles"; I should at least see an 'Average Disk Queue Length' counter of say 15 to 20 for some of the VDISKS through perfmon - and all these servers are pretty busy SQL Servers.