I picked 16 for two reasons, most of our hosts have a max queue depth of 32, so 16 is the 50% mark, and also 4 years ago (dated info by now, 32 bit windows 2003 with PCIX HBAs) when we did IOmeter testing on our T800s the queue depth to IOPS relationship showed steady improvement from 1-20 queue depth, and then hit a point of diminishing returns. While we could push the queue depth as high as 64... there was no real benefit to doing so past 20. This seemed to be a host issue, as we could continue to add more hosts to the test storage and each host would get similar results, even when they were benchmarked in parallel.
_________________ Richard Siemers The views and opinions expressed are my own and do not necessarily reflect those of my employer.
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