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Re: 400 000 mails in 12 Hours

On Thursday 27 February 2003 15:02, Guus Houtzager wrote:

> I saw your post on debian-isp containing the following:
> On Thu, 2003-02-27 at 17:26, Fraser Campbell wrote:
> > Whatever MTA you use I'm sure you'll need to do some tuning.  We had a
> > default postfix install that would choke when it had 1,000 messages in
> > the queue.  It would take up to 3 hours to deliver an email that should
> > have been instantly delivered.  Now that we've tuned that client's
> > postfix a bit it instantly delivers messages even when there are 2 to 3
> > thousand messages in the queue, and without noticable load being added to
> > the machine.
> Could you please tell me which options you tweaked to get this speed
> increase? The mailservers we use are having the same problem, and if it
> can be fixed, it saves me some whining customers complaining about
> emaildelays :)
> Thanks very much in advance!

I'm folllowing up to debian-isp just in case others are interested.  These are 
the steps that I took:

- upgrade postfix (that helped marginally, probably because the upgrade
  switched the default queue manager from qmgr to nqmgr)
- increased the process limit for smtp deliveries from 50 to 100, this is in
- we were running a 2.2 kernel so we upped the open files limit to 16384
  (default on 2.4 kernel)

  echo 16384 > /proc/sys/fs/file-max

- installed more RAM, during mailing list runs postfix was maxing out the
  128MB that was installed  (basically it seems to just use 128) after
  upgrading to 512MB of RAM the usage rarely goes over 128MB but it gets close
  enough that 128MB alone can't do the job

So in answer to your question (except for the resource issues) all we did was 
up the maximum number of smtp processes and switched to nqmgr from qmgr.

Here is the difference that it made, time to deliver emails in a 24 hour 
period to changes:

- 18.3% within 1 minute
- 20.0% within 2 minutes
- 20.7% within 3 minutes
- 21.6% within 4 minutes
- 22.2% within 5 minutes
- 61.2% within 30 minutes
- 88.5% within 1 hour,

Time to deliver emails in a 24 hour period after changes:

- 48.7% within 1 minute
- 68.0% within 2 minutes
- 89.2% within 3 minutes
- 95.3% within 4 minutes
- 98.4% within 5 minutes
- 98.7% within 30 minutes
- 99.5% within 1 hour

As you can see after changes more mail was delivered within 2 minutes than 
what could previously be done in 30 minutes.

Hope this helps.
Fraser Campbell <fraser@wehave.net>                     http://wehave.net/
Brampton, Ontario, Canada                        Linux 2.4.20 AuthenticAMD

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