[Dovecot] enourmous amount of disc writes

[Robert Schetterer]

Rainer Sigl schrieb:
> Hi Robert,
> many thanks for your answer!
> Yes I'm aware of the necessity to upgrade the complete system. Beside
> this I wanted to search for a quick solution. Upgrading the system
> entails many other things and is in my eyes not possible on the living
> system.

look for parameters in dovecot.conf example which might help you
with your problem

> Did you ever measure the ioactiviy with iostat on your machine?

no i havent, why should i ,its running fine since years, i have a meassure
from an nearly equal server
which runs sharedweb apache2, it shows nearly null
iostat, only during a rsync back there are a few outbreaks
but that might be not comparable to a imap server

> Please tell me the output values. Which hardware do you use?
> I have a RAID5 with 3ware 7000 series.

i have 3ware 9550SX SATA-RAID

> Regards
> Rainer
> 
> 
> Robert Schetterer wrote:
>> Rainer Sigl schrieb:
>>> Hi List,
>>> on my mailserver (exim4, dovecot 1.0.0, postgresql, ubuntu dapper, about
>>> 500 users) I record an enourmous amount of disc writes (up to 18000
>>> blocks written each second) in the time where most of users are active.
>>> This IO activity causes wait-states on the disc interface (RAID5) and
>>> finally slows down my mailmachine. Is there a explanation for these disc
>>> writes respectively is there a possibility to minimize this activity.
>>> Stopping Dovecot on this machine causes stopping most of the disc
>>> activity.
>>>
>>> Regards
>>> Rainer Sigl
>>>
>>>
>> Hi Rainer first you should upgrade to the latest stable of the 1.x branch
>> or better 1.1.x, also dapper is very old perhaps try hardy
>>
>> then retest, i run 2000 users on suse with dovecot 1.0.15 and mysql
>> on sata 3ware hardware raid 1 500 GB on ext3 without any problems
>>
> 


-- 
Best Regards

MfG Robert Schetterer

Germany/Munich/Bavaria