Re: raid io requests not parallel?

From: Jonathan Baccash
Date: Sun Jul 16 2006 - 18:56:03 EST

Because a single read not only goes to just one disk, it is sent to
the disk with the lowest expected seek time for that request. This
cuts average read time in half, on average.

(See drivers/md/raid1.c::read_balance().)

Thanks Chuck! That is making some sense, although I think I'll have to
read and think about it some more before I quite understand.

You didn't post any benchmarks showing results for single write to a
single disk.

I didn't think I could get any repeatable results for a single write,
so I was trying to understand what is happening based on runs of
longer writes.
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