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AW: qmail-send nearly stops delivery

To: <qmail@list.cr.yp.to>
Subject: AW: qmail-send nearly stops delivery
From: "Matthias" <matthias@pwn4g3.de>
Date: Tue, 29 May 2007 12:36:35 +0200
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-----Ursprüngliche Nachricht-----
Von: Feizhou [mailto:feizhou@graffiti.net] 
Gesendet: Dienstag, 29. Mai 2007 06:41
An: Matthias Jambor; 'Qmail List'
Betreff: Re: qmail-send nearly stops delivery

Matthias Jambor wrote:
> dear list,
> 
> we experience problems with one of our qmail-servers since a few days.
> It is a normal qmail-installation with the spamcontrol-patch. It 
> delivers mail to the local vpopmail-server or to external mailserver per
smtproute.
> 
> Sometimes qmail-send nearly stops delivery. The queue grows until a 
> few thousands of mails are waiting to be done.

few thousand preprocessed?

> At first we configured an default smtproute to an external relay-server.
> Then we installed bind (i know, tinydns would be better) for faster 
> name resolution.

you mean dnscache

> Both did not helped.
> Then we reduced concurrencyincoming from 200 to 10-25. After that 
> qmail-send deliverd the mails so that the queue decreased to a normal
value.
> Starting or stopping qmail gave no improvement. Neither did force 
> delivery (tcpok, kill -ALRM qmail-send).
> 
> We have to increase the concurrencyincoming back to something about 100.

Looks like an i/o efficiency issue.

> 
> Local system:
> Quad Opteron Processor 265
> 2G Ram (always enough free mem left)
> Adaptec AAC-RAID (Rocket)

More information on disk subsystem please.

> 
> Kernel version: 2.6.18.3 #1 SMP
> OS: debian 3.1 (qmailer was compiled from the sources, no 
> .deb-installation)
> 
> Average Deliveries last 24h: 13.8 kmsg Average Deliveries last month: 
> 7855.0 msg
> 
> Just ask if I have have to give you more information.
> Every help is welcome.
> 
> The picture is made from qmailmrtg7 out of the multilog-logfiles.

Just the max concurrency is useless...you need to compare deliveries against
concurrency and also injection rate.

It appears to me that this is a 'seasonal' thing and not a constant thing.
If you really want to make sure queues never build...please tell us that
filesystem the queue is on and the disk subsystem and consider using the
ext-todo patch or big-ext-todo patch (who one depends on your filesystem
although on Linux all should have directory index support by
default) which should make sure qmail-send is busy handling deliveries and
not processing the queue.


Hi Feizhou,

there were about 30,000 Mail in the queue and about one third was not yet
preprocessed.
I really meant dnscache.

I think that the problem ist solved know. But I will try to use the ext-todo
patch or big-ext-todo patch.

Thanks a lot for your help,
Matthias


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