From: Andreas Grimm (grimm.andreasyahoo.com)
Date: Tue Oct 30 2007 - 09:49:38 CDT

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Hello postfix-users,

maybe a short note for the linux users, because even after i applied the stress tips from Wietse, the server was slow. So i tried to run more processes and experienced problems running more than 900 simultaneously processes of smptd. I saw something like this in my error log:
Oct 29 10:16:44 mx-01 postfix/proxymap[29060]: fatal: accept connection: Too many open files
Oct 29 10:17:12 mx-01 postfix/anvil[29063]: fatal: accept connection: Too many open files
The server handled 1300 connections per minute with a maxproc of 1200, and wasn't reachable per smtp after the above error, so i reduced back to 800, but the delay was horrible when a botnet hit the server. I solved the problem by recompiling the kernel. You have to edit:
include/linux/fs.h, set INR_OPEN to 4096 (is 1024)
and
include/linux/limits.h, set NR_OPEN to 4096 (is 1024)
After rebooting i increased the maxproc in master.cf to 1500, the error was gone, the server handles up to 2600 connections per minute, and the delay is tolerable (<=3s).

Wietse Venema <wietseporcupine.org> wrote: Noel Jones:
> One very minor typo correction[1] and some extra fluff, to use or
> not, hopefully attached.
> This looks good, thanks.
>

Thanks. I have adopted the changes and gave some of your points
their own paragraph, to avoid clutter. The result is a nice balance
between the theory behind things and practical examples to keep
the reader on track.

 Wietse

>
> --
> Noel Jones
>
> At 03:27 PM 10/28/2007, you wrote:
> >I've taken away some from working on PHP, and written up a document
> >that explains Postfix SMTP server overload, how to avoid it, how
> >to minimize its impact on legitimate mail, and how to automate the
> >process with stress-adaptive behavior (now also available as a
> >patch for Postfix 2.4 and 2.3).
> >
> >http://www.porcupine.org/postfix-mirror/STRESS_README.html
> >
> >Bugfixes are welcome.
> >
> > Wietse

[ Attachment, skipping... ]

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