dovecot - Dec 2020 - ulimit -n vs client_limit vs process_limit

As many of my users are accessing their mail remotely, I've seen
service loads increase and came across this log messages which I
haven't seen before

 	imap-login: Error: socketpair() failed: Too many open files: user=<*>,
...

I gather I have to increase file descriptor limits, which is currently
set to match

 	default_client_limit = 1000

What should I set "ulimit -n" relative to client_limit? Or perhaps
I've roofed

 	service imap-login {
 		process_limit = 2
 		...
 	}

and should adjust that?

Joseph Tam <jtam.home at gmail.com>

You need to adjust LimitNOFiles (or ulimit -n). Dovecot needs more file
descriptors than just the ones used by imap-login process, so it is a good idea
to consider setting it to at least 3x time the value.

Aki
> On 17/12/2020 04:57 Joseph Tam <jtam.home at gmail.com> wrote:
> 
>  
> As many of my users are accessing their mail remotely, I've seen
> service loads increase and came across this log messages which I
> haven't seen before
> 
>  	imap-login: Error: socketpair() failed: Too many open files:
user=<*>, ...
> 
> I gather I have to increase file descriptor limits, which is currently
> set to match
> 
>  	default_client_limit = 1000
> 
> What should I set "ulimit -n" relative to client_limit? Or
perhaps I've roofed
> 
>  	service imap-login {
>  		process_limit = 2
>  		...
>  	}
> 
> and should adjust that?
> 
> Joseph Tam <jtam.home at gmail.com>

Hi Joseph,

we set following value in the system service file for dovecot:
 
# We have trouble with `Too many open files':
LimitNOFILE=8192

Jens

    
>     imap-login: Error: socketpair() failed: Too many open files:
user=<*>, ...