on Sun, Sep 28, 2003 at 05:48:36PM -0700, Robin Lynn Frank ([EMAIL PROTECTED]) wrote:
> From 9/18 till 9/24 we were being hammered with a huge spike in
> traffic that our server handles for 6 domains. In order to allow a
> per user config, we used postfix, forward files, procmail,
> spamassassin and tmda.
>
> Postfix handled the load with no problem. TMDA kept chugging along.
> Procmail and spamassassin didn't fare as well. From what I can
> determine, postfix delivered to procmail where things , ah, err, got
> constipated. That is until spamassassin pooped on its own lock file
> and procmail's pipe burst. Surprise, there were a boatload of emails,
> some as old as five days. In the 20 minutes it took me to get back to
> the office, we bounced that boatload of messages.
What were the specific characteristics of the choke-up? I've had to
have the box filtering my mail killed (hard boot, no shutdown) twice
over the past summer due to spamassassin filtering load, during the
SoBig traffic spike. We've weathered Swen fine.
System here was running exim 3, spamassassin, and local filtering for
some accounts via procmail. Three accounts are also served by fetchmail
from remote POP3 servers, with mail loads as high as 300-600+ messages,
though fetches are generally capped at 20-40 per pull, polling ever 3-4
minutes. I also pulled my own fetchmail polling out of the systemwide
configuration, and feed the output directly into procmail.
At one point system load climbed above 120, on this 160 MHz PA-RISC box.
There are several tuning options to set:
- Spamassassin has a max-children parameter. Use this. Once you've
got a few child processes running, you're probably saturating CPU
and/or bandwidth. We set this at 10.
- Similarly, exim (or your MTA) will have a concurrency limit. Set
this as well. We've since upgraded to exim4, but IIRC the level was
10.
- Depending on your OS/distro configuration, it's possible to set
per-user limits through ulimit or /etc/security/limits.conf. We
capped 'mail' at 30 (10 exims, 10 SAs, and some slack).
At this point the system was running reliabily without going into high
load, even under very high mail traffic.
Pre-filtering mail with executable attachments and rejecting these at
SMTP connect will also greatly reduce system load.
Another setting you're goin to want to look at are your system max files
and max processes values. GNU/Linux is notable for setting these lower,
and handling resource starvation worse than, FreeBSD. 2.4 kernels
increase these limits and allow for compiled-in and/or dynamic
configuration of these values.
Useful information for those using TMDA in conjunction with other tools.
Peace.
--
Karsten M. Self <[EMAIL PROTECTED]> http://kmself.home.netcom.com/
What Part of "Gestalt" don't you understand?
I forgot my mantra.
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