[Dovecot] help: "dovecot: pipe() failed: Too many open files"

[Jake Grimmett]

Dear All,

I'm having an intermittent problem, with dovecot slowing to a crawl. 
Restarting dovecot fixes the problem.

Looking at the maillog, I see loads of these errors....

dovecot: pipe() failed: Too many open files
dovecot: Temporary failure in creating login processes, slowing down for now
dovecot: Created login processes successfully, unstalling

looking at the processes, I can see ~200 imap-login's and about ~700 imap's
there are 1000 email accounts on the server - half of which are in regular 
use.

The server is Dell PE1950 running dovecot (1.0.7-2.el5) as supplied with 
Centos 5.2 (~Redhat AS 5.2) in 64 bit mode. I've upgraded the server from 4 
to 8GB of RAM, and from a dual core 1.5Ghz xeon, to a quad core 1.5GHz xeon, 
and this does not seem to help.

The following settings were increased by me to try and stop this problem - but 
did not have an obvious effect:

login_process_size = 128
login_process_per_connection = yes
login_max_processes_count = 512

Other parameters were left commented out:

#max_mail_processes = 1024
#auth_process_size = 256


If anyone has any ideas about where I might be going wrong, please let me 
know..!

many thanks

Jake

-- 
Dr Jake Grimmett
Head Of Scientific Computing
MRC Laboratory of Molecular Biology
Hills Road, Cambridge, CB2 0QH, UK.
Phone 01223 402219
Mobile 0776 9886539