On 11/06/12 13:45, Timo Sirainen wrote:
On 11.6.2012, at 13.19, Angel L. Mateo wrote:

Proxying is done by imap-login process, not imap process. For login processes 
there are different recommendations.

        What are those recommendations? The ones at 
http://wiki2.dovecot.org/LoginProcess?

Yes.

        Let's suppose... I have 4 mainly imap backend servers (but they admit 
also pop3 connections) with a process_limit of 5120 for service imap (and 
default_client_limit of 1000 applied to pop3). And I have 2 director servers 
(configured as active-active behind a load balancer), so I need director 
servers to handle (more or less) 10240 imap connections.

        What is it better for the director's? Increasing process_limit for 
imap-login (so each process should handle less connections) or increasing 
client_limit (less processes handling more connections each)?

If you increase process_limit to more than the number of CPU cores you have, 
then you increase the number of context switched done by the kernel, which 
decreases your performance. So I'd say increase client_limit.

I'm trying to configure it this way, so I have configure process_limit to the number of cores and client_limit big enough to attempt the maximum number of connections configured at the backends.

In my test environment I have configured (this is extracted from doveconf -n output):

service imap-login {
  client_limit = 10740
  executable = imap-login director
  process_limit = 1
  process_min_avail = 1
}

When I made the first connection, there's no problem, but if I try a second while the first is still open, I get:

Jun 13 13:09:12 myotis40 dovecot: master: Warning: service(imap-login): client_limit (1) reached, client connections are being dropped

        Why is telling me that client_limit is reached? What client_limit is 
used?

--
Angel L. Mateo Martínez
Sección de Telemática
Área de Tecnologías de la Información       _o)
y las Comunicaciones Aplicadas (ATICA)      / \\
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