Iustin Pop wrote:
On Wed, Apr 04, 2007 at 07:11:50PM -0400, Bill Davidsen wrote:
You are correct, but I think if an optimization were to be done, some
balance between the read time, seek time, and read size could be done.
Using more than one drive only makes sense when the read transfer time is
significantly longer than the seek time. With an aggressive readahead set
for the array that would happen regularly.
It's possible, it just takes the time to do it, like many other "nice"
things.
Maybe yes, but why optimise the single-reader case? raid1 already can
read in parallel from the drives when multiple processes read from the
raid1. Optimising the single reader can help in hdparm or other
benchmark cases, but in real life I see very often the total throughput
of a (two drive) raid1 being around two times the throughput of a single
drive.
Why optimize the single thread case? Any process which has low CPU
requirements (by current standards) becomes i/o bound. The obvious
candidates are grep, sed, dd, or awk. And don't overlook the benefits of
reliable swap.
Test script modifications taking place as I type, I post the script and
some results later this week, barring urgent support issues.
--
bill davidsen <davidsen@xxxxxxx>
CTO TMR Associates, Inc
Doing interesting things with small computers since 1979
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