[Dovecot] Performance settings for 500-1000User/per day

[Timo Sirainen]

On Mon, 2011-06-20 at 15:16 +0200, Denny Schierz wrote:

> we have 2.0.13 running and most works well, but today we had some minor
> problems: The IMAP login process takes sometimes to much time. Over
> webmail (Roundcube 0.5.0.3) login wasn't sometimes possible, the normal
> clients hasn't any problems, until they login.
> 
> We had only ~ 20-30 active accounts, but 50-60 sessions. The most are
> Apple products (Ip*/Mac/. ..)because they have 4 sessions or more open.
> 
> Also we had ~212 processes with:
> 
> dovenull  2065  4364   0 14:50:32 ?           0:00 dovecot/imap-login
> vmail  2403  4364   0 14:58:31 ?           0:00 dovecot/imap

I suppose that means you had 100 IMAP clients simultaneously connected
using SSL, which used up all imap-login processes with default settings.
There should have been a warning logged about it though.

Switch to high performance login process mode
(http://wiki2.dovecot.org/LoginProcess) or increase service imap-login
{ process_limit }.