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From Peter Schuller <>
Subject Re: Does "concurrent_reads" relate to number of drives in RAID0?
Date Fri, 18 Mar 2011 00:40:32 GMT
> The reason for this is that you want to be able to saturate your
> storage subsystem, and that means keeping all spindles working at all
> times and efficiently. This is accomplished by ensuring you are able
> to sustain a sufficient queue depth (number of outstanding commands)
> on each device. This in turn, in the case of a RAID0, means
> multiplying the target maximum queue depth with the number of drives.

(But this is all predicated on the operating system actually letting
the I/O requests pass through to the device, which is why I replied
about choosing the deadline or noop scheduler instead of cfq.)

/ Peter Schuller

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