Slow random I/O performance in Windows 2008 R2 with Qlogic 2560

[Steve Modica]

Running gross tests like disk benchmarks only tells you a little about the problem.
Ideally, you’d have something that let you look at individual IOs so you could see their latency and size.
For example, perhaps in the new OS, you aren’t getting the same IO size as before. That might be a simple tuning issue. Perhaps you are running out of a disk IO resource after a short period (you would see the IOs stay fast and large, but perhaps stop coming as rapidly since they are queuing up for buffers to allocate).

On Mac OS X, there’s dtrace, so you can gather a lot of information like this. I’m not a windows guy.

Steve

Steve Modica
CTO, Small Tree Communications

[Jonathan Eason]

Sounds like you will need to re-tune the system. I would start with narrowing down the i/o paths to single routes and perform a baseline benchmark with ONE tool. Windows Server has built-in Performance Monitoring or there is Process Monitor that you can download via the Windows Sysinternals website. I prefer Process Monitor becuase it is easier to use. If you have both environments running it should be relatively easy to isolate areas of latency within your applications.