[Dovecot] fd limit 1024 is lower in dovecot-1.1.1

[Jack Stewart]

Zhang Huangbin wrote:
> Daniel L. Miller wrote:
>> Zhang Huangbin wrote:
>>> Hi, all.
>>>
>>> I just upgrade from 1.0.15 to 1.1.1 in a test box(RHEL 5.2, x86_64).
>>>
>>> after upgrade, i got this warning msg:
>>>
>>> ----8< ----
>>> # /etc/init.d/dovecot restart
>>> Stopping Dovecot Imap:                                     [  OK  ]
>>> Starting Dovecot Imap: Warning: fd limit 1024 is lower than what 
>>> Dovecot can use under full load (more than 1280). Either grow the 
>>> limit or change login_max_processes_count and max_mail_processes 
>>> settings

>> I'm just guessing - but reading that warning it appears to me that 
>> Dovecot is saying that as it is configured, it can consume more O/S 
>> resources (I assume fd is "file descriptors") than the O/S is 
>> currently configured for.  So you need to DECREASE your dovecot max 
>> processes to decrease the (potential) system demands - or increase 
>> your O/S settings.
>>
>> Daniel
>>
> 
> I think so.
> 
> I just decrease the processes, it works now.
> 

Hi,

Just as an FYI, for some versions of linux (i.e. RHE) you need to set 
the process limit - ulimit unlimited is not enough. 1024 is the default 
number of open file descriptors.

One of the ways to solve this is by running 'ulimit -n X' in your init 
script before starting the program. Within RHE, another way is to 
configure /etc/security/limits.conf by putting something like this into 
the file:

*    hard    locks     8192
*    hard    nofile    8192
*    soft    locks     4096
*    soft    nofile    4096

This allows for processes to run with 4096 file descriptors by default 
and the user process can increase it to 8192 via ulimit. 
/etc/security/limits.conf can also be configured on a per user basis 
which is also nice.