Re: raid io requests not parallel?

[Jonathan Baccash]

> 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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