[Dovecot] default client_limit

Micah Anderson micah at riseup.net
Mon Sep 23 19:32:21 EEST 2013

I recently upgraded my dovecot from 2.1 to 2.2, and when I started, I
received this message:

doveconf: Warning: service auth { client_limit=1000 } is lower than required under max. load (1024)

Searching through my configs, I do not have 1024 set anywhere. 

In order to stop this I set client_limit=1024 in my auth{} block... this
seemed odd that the defaults disagreed with each other.

However, it made me realize that my system could probably handle more,
if it were properly tuned, and the different limit settings at their
defaults are probably smaller than they could be for my server and the
load it is under. So, I'm wondering how I can accurately set some of
these values?

The different possible things that can be set are:

default_process_limit (for some reason I have this set to 256)
default_client_limit (default)
default_vsz_limit (I have this set to 512M)

for the imap-login service, I have:
  service_count = 0
  process_min_avail = 10
  vsz_limit = 512M

for service pop3-login, these are set:
  service_count = 0
  process_min_avail = 10
  vsz_limit = 512M

for service imap,
  process_limit = 2048

service auth, I've just set the client_limit=1024

I've also got a ulimit -n set to 2048 and in my sysctl.conf, I have the

fs.inotify.max_user_instances = 2048

because I was seeing this in the logs:
Warning: Inotify instance limit for user 8 (UID mail) exceeded, disabling. Increase /proc/sys/fs/inotify/max_user_instances

What I am looking for is a few things:

 . is there a formula for setting a proper value for some of these?
 . will dovecot warn me when I've reached a limit, so I can adjust

thanks for any suggestions or improvements, I'm pretty sure this system
can handle a lot more than it is doing right now, I just am unclear on
how to tune it up to do that.


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