A few days ago, I had an old Windows box that worked as an inbound mail
relay start to fail, so I figured I'd replace it with two OpenBSD boxes
in a CARP pool.
It's a big VMware shop, and I've mostly had good luck running OpenBSD
under ESX, so I set up two 4.6 amd64 VMs and put them into production.
The site gets about 30-40k messages per day. During periods of heavy
load, the load average would occasionally spike over 12, and Sendmail
would dutifully stop accepting new mail until it slowed down.
Unfortunately, since this box is just a relay (second hop inbound), that
meant the first hop inbound would start to just queue messages since the
second hop wasn't responding.
I figured maybe it was a VMware problem, so I cranked the load average
threshold to 50 to work around the problem, and built a physical box (an
HP DL360 G4, 2gb RAM). This was also the day I got my 4.7 CDs, so I
installed 4.7.
The physical box is doing much better, but the load averages are still
much higher than I'd expect, generally never going below 1. I realize
load averages are usually lies, but the box seems to be working a lot
harder than I'd expect. For reference, the Windows box I replaced was a
DL380 G2, with a single P3-1.4 and 256mb RAM, and it was running a
commercial antivirus product based on Sendmail.
What can I do to diagnose the performance bottleneck? The CPU is mostly
idle.
- Sendmail performance and OpenBSD Steve Shockley
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