Tuning Suggestions

Michael Bacon baconm at duke.edu
Tue Jun 10 14:29:02 EDT 2003

I can't tell precicely from your report, but it may have something to do 
with a problem we've seen several times.

In case of memory exhaustion, Cyrus can begin to behave badly.  What 
happens is the master ends up with an incorrect number of available 
processes, such that it believes there are sufficient workers to handle the 
incoming connections, when in fact there are not.  The easiest way to check 
this is to look at those times when you see failed connections, and look to 
see if you've had any memory bottlenecks shortly before then.  If you see 
any problems with memory exhaustion, it's generally a good idea to restart 
the cyrus server.  (If you're daring, you can attach to it with a debugger 
and manually modify the Services[] array, but that's a bit dicey...)


--On Tuesday, June 10, 2003 10:51:19 -0400 John Straiton 
<jsmailing at clickcom.com> wrote:

> Funny that I haven't found much in the lines of tuning suggestions for
> Cyrus on googlegroups or in the info-cyrus archives but I think I may be
> in need of it. I'm using a 4.8-STABLE FreeBSD machine, Dual 600Mhz with
> 1.5GB of RAM and plenty of RAID5 space.
> We use Cyrus+Postfix+AMAVISd+SpamAssassin and are rather happy with the
> combination. Our postfix feeds 5K addresses into 4K cyrus mailboxes.
> Load on the machine usually rides between 0.5 and 1.0. top normally
> reports around 60%-70% idle levels. In normal operations, I'll see
> around 30-50 connections to the server at all times since most of our
> users use pop3. We also limit mailboxes to no more than 25MB other than
> employees. All employees use IMAP tho'. Our entire message store only
> contains 5.6GB of messages.
> The problem I'm having started about 2 days ago when our Nagios
> monitoring started reporting that connectivity to the server (pop3/imap)
> was failing. Then we'd get recovery notifications immediately after.
> Kinda like the server was only unable to handle itself for a brief
> moment and then would get back to business. I also personally noticed
> that I'd get notifications in Outlook that some of the 5 IMAP
> connections I keep to the server would time out periodically. I would
> assume since send/receives occur every 5 minutes that these are not idle
> timeouts.
> This has never been a problem before, but obviously with a company
> that's still growing, every day we have more users on the system than
> the day before. I fear that something on the machine or in cyrus'
> configuration is holding us back.
> I come seeing suggestions for things I could check or change in order to
> resolve this before it gets to being more of a problem than it is. I
> figured I'd start with Cyrus and then move down to the OS level.
> Thanks,
> John Straiton
> jks at clickcom.com
> Clickcom, Inc
> 704-365-9970x101

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