[Dovecot] enourmous amount of disc writes

[Patrick Domack]

Dunno how much this applys to a local drive, but:

I run dovecot for about 40k users over nfs. Default install of redhat el5

The version of dovecot shipped with redhat caused all kinds of user  
issues, so swapped it out with a pre 1.0 release of dovecot that I  
knew was good.

About a year ago, I upgraded it to dovecot 1.1.3, and I freaked out,  
cause we have no load on the mail/nfs servers at all. The nfs load  
dropped to only 6% of what it was doing. No user complaints,  
everything has been good for a year.

I was completely paranoid for a few days after the upgrade though,  
cause my stats dropped so much.

Quoting Rainer Sigl <sigl at mpe.mpg.de>:

> Hi Richard,
> many thanks for you answer.
> yes, this solution did we discuss as well. For a future testing system
> I will try this. But I can't use it on the living system in the moment.
> Regards
> Rainer
>
> Richard Hobbs wrote:
>> Hello,
>>
>> You might also want to enable "noatime" in the mount options for the
>> volume housing the data... if you're using maildir, this *could* reduce
>> the number of writes by half, theoretically!
>>
>> Richard.
>>
>>
>> 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
>>>
>>
>
> -- 
> -----------------
> Rainer Sigl,                      | email: sigl at mpe.mpg.de
> MPI f. extraterrestrische Physik, | phone: +49 (89) 30000-3557
> Postfach 1312,                    | fax:   +49 (89) 30000-3569
> D-85741 Garching, Germany         | web:   http://www.mpe.mpg.de/~sigl/