Calculating IOPS on physical server as virtualization candidate.

Posted on 2011-03-01
Medium Priority
Last Modified: 2012-08-14
I am working a project where I need to virtualize 30 existing physical servers.

I have collected perfmon data over the last week using logman including physical and logical disk counters.

I am currently looking at disk reads/sec and disk writes/sec, but these numbers aren't adding up to IOPS.    For example I have 1 server with a RAID1.  Perfmon says the reads/sec had an average of 6/sec over the last week, but the maximum was 656/second.   But this can't possibily be right if the maximum (without solid state drives) would be about 150-180/IOPS per second.

What microsoft counters can I use to calculate the average IOPS usage per logical or physical disk without having direct access to the physical hardware.
Question by:USWired
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chkdsk01 earned 1000 total points
ID: 35011957
If you already have a vCenter server you can install the guided consolidation plugin.  This lets you monitor performance of physical servers and it will give you a confidence rating showing you if the servers are good virtualization candidates.  I wouldn't use this entirely to base my judgement, but it helps.
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Duncan Meyers earned 1000 total points
ID: 35012410
You're on the right track. The most likely reason that you're seeing a peak of 656 IOPS on a mirrored pair is that RAID controller cache (or on-disk cache for that matter) has handle the peak workload.

You are correct regarding 150 to 180 IOPS But this is a sizing number. That is; your disks will handle 180 IOPS day in, day out without breaking a sweat. They'll handle up to 2 to 2.5 times that workload before response times become unacceptable, so you could see 360 to 450 IOPS per drive for 15k scsi or SAS drives.

Author Comment

ID: 35013137
Actually I found the numbers I was looking for which was Physical Disk - Disk Reads/sec and Disk Writes/sec as opposed to Logical Disk - Disk Reads/sec and Disk Writes/sec.
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by:Duncan Meyers
ID: 35013185
Thanks! Glad I could help.

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