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I'm not sure whether this sounds stupid or lazy, but I'm really not sure.

I have a problem with the performance of a VM setup (2008R2-64bit Hyper-V running a 2003R2-32bit Windows server) and I'd like to see whether the disk is the problem.

I want to time a C++ build. It will take x minutes on the real hardware and x+y minutes on the single VM running on this same hardware. (And, y is way too large, hence this question.) I guess I would want to run perfmon during each build and time some counters and then compare the results.

  • Should I run perfmon on the host or on the guest (for the build in the VM)?
  • Which counter(s) should I look at?
  • Should I consider anything besides perfmon?
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1 Answer 1

I'd say the most relevant counters are:

  • Disk Bytes/s
  • Current Disk Queue Length
  • Avg. Disk Queue Length

Benchmarking the disks (both virtual and physical) with ATTO may be worth a try as well.

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2  
Acutally no, the only relevant is pretty much "seconds/IO". The moment that goes up, the disc is overloaded - the rest needs a LOT of interpretation, this one tells you when the responsiveness goes down. For example - how big is too big for avg queue length? Depends on discs ;) I know a SAN that had 26x256 for queue size without problems. But Seconds/IO (which should be 0.00x) tells you in one number when things get bad. –  TomTom Sep 4 '12 at 12:13

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