<SNIP>
>Does having 6 4g drives produce more IO/sec  than 3 9g drives?
</SNIP>

Many years ago...

I accepted that it would be a good idea to switch from five pairs of
mirrored 670MB drives (3.3GB) to a single 5.4 HA disc array.  The primary
application consisted of many processes most of which did Image calls.
Reports started taking three to ten times as long.  :(

It took switching to two 2.7GB arrays to bring the run times back within
reason.

MPE was doing a very good job of scheduling processes for when data is
available from many drives.  Even though there are several spindles in the
disc array, it is the number of spindles that MPE can queue on that matters.

Lesson learned...

If you have a large number of independent processes, more small drives are
preferred to fewer large drives.

Digression...

I extrapolated this to the point where it should be a good idea to a very
large number use those un-marketed "Kitty Hawk" drives (20-40MB).  If only
there was enough back plane for the interface cards.

neal

Neal Kazmi ([log in to unmask])
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