[Dovecot] configuration guidelines.

[Jeff A. Earickson]

On Mon, 4 Sep 2006, Mart Pirita wrote:

> Date: Mon, 04 Sep 2006 10:25:13 +0300
> From: Mart Pirita <sysadmin at e-positive.ee>
> Cc: dovecot at dovecot.org
> Subject: Re: [Dovecot] configuration guidelines.
> 
> Tere
>> A few that look like they might need changing are:
>>
>>    login_process_size = 32
>>    login_process_per_connection = yes
>>    login_processes_count = 3
>>    mbox_dotlock_change_timeout = 30
>>    auth_count = 1
>>    client_workarounds =
>>
>> Does anyone have any pointers to reasonable values for those or other
>> settings?
>>
>>
> Well, I'm using the latest rc7 and have a same problem. Timo should give
> some clues about settings, something like:
>
> 1) Server for < 100 users,
> 2) Server for < 1 000 users,
> 3) Server for > 10 000 users and more, etc.
>
I too would like some guidelines, but I'll bet Timo has no clue about
different OS'es and numbers of users since there are so many variables.

My case: Solaris 10, dovecot rc7, imap and imaps, 3K users.  The knobs
I turn are:

login_max_processes_count = 1024
login_max_connections = 2048

I initially had to double the default numbers for late beta and early
rc versions, but have had to further raise these numbers in the last
day or so.  All 3K users are now back and pounding on my dovecot box;
dovecot has crashed twice today so far.  I'm watching carefully (and
wishing I had more idea about why I am hitting the "Login process died 
too early - shutting down" message, aka "too many open files").

For Solaris 9 and 10, I have had to boost the following kernel parameters
in /etc/system (followed by a reboot):

* double file descriptor limits for dovecot
set rlim_fd_cur = 65536
set rlim_fd_max = 131072

My two drachmas.

Jeff Earickson
Colby College