On Friday 07 November 2003 14:19, Scott Courtney wrote:
> I'm hoping someone can give me a mental whack on the side of the head to
> see what I'm overlooking in this situation with some Exim problems. The
> answer is going to be painfully obvious with 20-20 hindsight, but I've been
> working on this for three days, searching Google, poring over manuals, and
> it's just not popping out at me.
It's been a long time since this thread, but now that we have definitely
solved the problem I wanted to post back to the list, for the benefit of those
who might later find this problem thread with a search engine.
The performance problems turned out to be I/O bottlenecks from the disk drive.
Even though the system had a RAID striped array, it appears that the drives
are not all that fast (a brand new system from a major manufacturer whose
name I won't mention).
In any case, the issue was logging! We had a "moderate" level of logging
happening, using syslogd so that we could centrally collect logs on an admin
system that does some automated analysis.
Turns out that syslogd, even with buffering enabled in the syslogd.conf file,
isn't all that efficient at handling its disk I/O. Turning off the network
logging didn't help, because the problem was actually right there on the local
machine.
We improved performance quite a bit by having Exim do its logging to dedicated
flatfiles (using the log_file_path directive), but this still didn't completely
solve the problem. Finally, we simply reduced the logging level substantially
for normal message queueing and delivery. This limits some of what we can do
in the way of statistical analysis, but the performance of the system is now
quite acceptable and it's easily handling about 25000 messages/hour.
The more I work with Exim, the more I am impressed with its configurability and
flexibility. This is one great piece of software!
Thanks to everyone who posted in response to this thread. Your suggestions did
help us to finally narrow down the cause of the problem.
Kind regards,
Scott
--
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Scott Courtney | "I don't mind Microsoft making money. I mind them
courtney@??? | having a bad operating system." -- Linus Torvalds
http://4th.com/ | ("The Rebel Code," NY Times, 21 February 1999)
| PGP Public Key at http://4th.com/keys/courtney.pubkey
