[Mimedefang] BIG problems with mimedefang

[Matthew.van.Eerde at hbinc.com]

Lisa Casey wrote:
> I discovered
> that my max slaves was set to 10 and increased that to 30 hoping that
> would solve the  problem. It hasn't. Here's what I'm seeing. Things
> will be going along ok, then suddenly the server load will shoot up
> from 0.something to over 30! When that happens mail stops. A top
> shows something like this: 
...
> Mem: 512900K av, 509840K used, 3060K free, 0K shrd, 1800K buff
> Swap: 522072K av, 520104K used, 1968K free 5204K cached
> PID USER PRI NI SIZE RSS SHARE STAT %CPU %MEM TIME COMMAND
...
> 11859 defang 10 0 30572 20M 1852 D 6.3 4.0 0:10 mimedefang.pl
> 11657 defang 10 0 30172 9252 1820 D 3.0 1.8 0:07 mimedefang.pl
> 11652 defang 9 0 29184 8400 1832 D 2.9 1.6 0:07 mimedefang.pl
> 11759 defang 9 0 18888 7480 1748 D 1.5 1.4 0:06 mimedefang.pl
> 11705 defang 9 0 18884 5336 1828 D 1.3 1.0 0:06 mimedefang.pl
...

You never want to descend into swap on a mail server - it just makes things go from bad to worse.

Your mimdefang threads are around 25MB each (well, 20-30MB)
You have 512MB of memory.

Assuming that ALL of your memory goes to MIMEDefang, this means you should have an absolute max of (500 / 25) 20 mimedefang threads - you should set your MX_MAXIMUM to nothing higher than this.

In practice, you need memory for other things too... so probably 16 is a good number for you.

There are optimizations you can put in place to:
* make your mimedefang threads process mail faster so they become available faster
	run a local DNS server
	run the spool on tmpfs (and /tmp if you're using SpamAssassin)
* prescreen email more cheaply so that mimedefang has less to scan
	add virus checks before MIMEDefang
	add RBLs in sendmail
	add address verification

... various other tricks... check the wiki
http://www.mimedefang.org/kwiki/

-- 
Matthew.van.Eerde (at) hbinc.com               805.964.4554 x902
Hispanic Business Inc./HireDiversity.com       Software Engineer