Hello Timo,

I'm running dovecot-1.2.12/Maildir/LDAP-passdb/LDAP-prefetched-userdb and I'm experiencing "random" latency (which even seem to make squirrelmail timeout sometimes) at login without noticing particular load on the server.

LDAP backends are running fine as far as I know so I was investigating maybe mistuned limits :

Dovecot is configured (for ~3000 users) with

. each login processed in its own process :

  #login_process_per_connection = yes
  #login_max_connections = 256

. counts as :

  #login_processes_count = 3
  login_max_processes_count = 1024

  auth default {
  [...]
  count = 5
  }

I've got several questions :

1. how can I count more than login_max_processes_count processes ?

ps aux | egrep -i '(pop3|imap)-login' | wc -l

# 1031

2. could be my auth process count the bottleneck ? is there a rule of thumb to deduce it from the login process count ?

3. on dovecot login/master/auth design, is my understanding correct ?

• dovecot-1.2.x :

  . passdb and userdb lookup are done by the auth process, on behalf of either the login process which wants to know if the client's password is correct or of the master process which wants to check if it was actually correct and which wants to have the userdb info.

  . client connection fd is sent to the master which creates the mail process and transfers the fd to it.

• dovecot-2.x :

  . client connection fd does not go through the master anymore but through a socket in the login/ directory

  . it's the mail process which ask the auth process for the userdb lookup

4. with LDAP backend using {CRYPT} passwords dans with plaintext auth enabled in dovecot, is the clear password crypted before comparing it to the LDAP crypted password or does dovecot try to simply bind to LDAP with the clear password ?

Thanks

-- Thomas Hummel | Institut Pasteur hummel@pasteur.fr | Groupe Exploitation et Infrastructure