> 2) in the mirror case the write speed is cut by half, and the read
> speed is the same as a single disk. I'd expect about twice the
> performance for both reading and writing, maybe a bit less, but
> definitely more than measured.
I wouldn't expect mirrored read to be faster than single-disk read,
because the individual disks would need to read small chunks of data
with holes in-between. Regardless of the holes being read or not, the
disk will spin at the same speed.
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