Capturing I/O traces

Fluffles etc at
Tue Jan 9 05:23:15 PST 2007

Hello list,

I was wondering if any method is known to "capture" I/O traces. My goal
is to be able to simulate I/O access patterns generated by applications
such as MySQL or KDE and compare these to other storage systems. This
way i can provide more realistic benchmarks (not synthetic) without
actually running the application i'm testing. For example, I would like
to capture the I/O that occurs when KDE boots, and then be able to
reproduce this I/O access on say a gmirror and graid3. This way i can
gather more realistic benchmark results. On Windows several commercial
applications exist that 'simulate' access patterns used by applications,
i was wondering if any BSD/Linux equivalent exists.

One thought that comes to mind is the gnop geom class; with verbose mode
this provides a text log of all the I/O accesses. But it does not
provide the exact time/concurrency etc, only the offset, length, I/O
action (read/write) and the serial order of those requests. And even
with this information it's not easy to reproduce them; i would have to
write an application that reads this log and then be able to reproduce
it. I was hoping to find a more elegant solution. If you guys know of
any, please share it with me. :)



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