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For an I/O capacity study I'm working on, (on a windows server 2008R2 system) I'd like to gather absolute I/O counts for a given physical (or logical) disk over a specific period of time. When I look at perfmon "counters", I see lots of I/O/sec type "counters", but I can't see any of the absolute counters these rates must surely be derived from.

Does anyone know a way to collect raw I/O counts (totals, not a rate)? I suppose I could collect the I/O per second "counters" once a second, then sum them over the interval, but that seems pretty clumsy, and I worry that a rate counter may use a sliding window average for calculating its rate.

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What counters are you looking at and what are you trying to measure? – mrdenny Mar 22 '13 at 20:29
Well, as an example, If I look at the PysicalDisk set of counters, the "Disk Reads/Sec" and "Disk Writes/Sec" are the closest. I'd really like that data without the "/Sec". I'm trying to measure the total number of I/O operations performed for a specific device over a a specific duration. – graham Mar 22 '13 at 22:14
yeah, there's no perfmon counter for those. You'd have to gather the data over a period of time and sum it up. It won't be exact but it'll be close. You can setup a data capture to a SQL Server table, then just sum the values. – mrdenny Mar 23 '13 at 0:41
Thanks for the answer. That's pretty frustrating though, since in order to calculate Disk*/sec it'd need to collect the very data that I'm looking for, do some math, then throw it away. Back to the ol drawing board I guess. – graham Mar 25 '13 at 16:38

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