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Subject: SCSI, U2W in particular?, and poor performance...
From: Justin Robertson (zululinux.com)
Date: Sat Mar 04 2000 - 20:39:45 CST

  Using fsstone and smtpstone, I've noticed some 'quirks' in performance.
For example, on an extremely low end Celeron 400 with 32MB of ram and a
cheap 6.4gig IDE HD, I can succesfully create/delete 1024 files using
fsstone in about 2 seconds. Using smtp-source I can send 1000 15k messages
in 44 seconds, using only 2% of the CPU. Now, this is good, however, when
the same tests are attempted on a conciderably higher end box, 800MHz,
768MB of RAM, and 10,000rpm 18.2gig U2W SCSI HDs, the results are... well,
far lower then the low end machine. It takes 14 seconds to perform the
same fsstone test, and well over 7 minutes to perform the same
smtp-source test. Perplexed I attempted a series of CPU and HD tests on
the high end machine, and it was performing as would be expected. Is there
something about the way that postfix reads/writes data that is 'iffy' in
the SCSI drivers at this point? This would make no sense to me... I've
check with another individual whom is using a different SCSI controller
card, ncr xxx vs. my adaptec a2940u2w, and the results are comprable. What
gives? Anybody have an idea? I could just put everything on to a RAM disk,
but the point is that a crappy machine shoudln't be smoking the highend
box.

Justin Robertson
<zululinux.com>