[Dovecot] Another "Too many files open" post

Stewart Dean sdean at bard.edu
Wed Dec 21 15:50:46 EET 2005

It's worth pointing out that /any/ system worth its salt has user 
limits...for # files, memory, stack size, etc, etc.....so this is a 
generic situation that could bite the sys admin on any system when users 
start using resources heavily.  In IBM's AIX, the file that sets this is 
/etc/security/limits....and I believe it takes effect immediately when 
changed there or at least at the next user's login....there is a default 
stanza and then stanzas (optional) for each userid.....

Andy Cravens wrote:

> I'm running Solaris 9 Sparc with Dovecot alpha 5 and using maildir 
> format..  I noticed in the log file the following error:
> dovecot: Dec 20 15:54:18 Error: imap(xxxxxxxx): 
> open(/export/home/xxxxxxxx/mail/.Sent 
> Messages/cur/1135013649.002916.mbox:2,Sab) failed: Too many open files
> I called the guy and asked him what he was doing... synching his 
> folders.  It hung for a while but finally finished.
> I searched the archives and found some related info from Jeff Ballard:
> >Actually on Solaris 9 you want to put something like this in 
> >/etc/system:
> >
> >set rlim_fd_cur = 32768
> >set rlim_fd_max = 65536
> >
> >That sets the current fd's to 32k and max to 64k.  Unfortunately, to 
> >take effect you'll need to reboot.  After the reboot, ulimit -a 
> should >show that nofiles(descriptors) is 32768.
> >
> >-Jeff
> And I found this from Jeff Earickson:
> >I ran into this problem with alpha4 on Solaris 9.  I doubled the
> >following dovecot settings:
> >
> >login_max_processes_count = 256 (was 128)
> >login_max_logging_users = 512 (was 256)
> >
> >and the problem went away.  I carried these numbers forward intoalpha5,
> >and it has been working fine.
> I changed my /etc/system file but have not rebooted yet.  Also, on 
> Jeff Earickson's post, I looked at my dovecot.conf settings and 
> they're basically default which means everything in the "Login 
> processes" section is commented out.
> I have 10 users on this system and will hold off migrating any more 
> until I can resolve this problem.  By the way, my "ulimit -a" shows 
> "open files" at 256 which seems low.
> # ulimit -a
> core file size (blocks)     0
> data seg size (kbytes)      unlimited
> file size (blocks)          unlimited
> open files                  256
> pipe size (512 bytes)       10
> stack size (kbytes)         8192
> cpu time (seconds)          unlimited
> max user processes          29995
> virtual memory (kbytes)     unlimited
> Any advice would be appreciated.  I can't reboot for a few more days.

Stewart Dean, Unix System Admin, Henderson Computer Resources 
Center of Bard College, Annandale-on-Hudson, New York  12504  
sdean at bard.edu  voice: 845-758-7475, fax: 845-758-7035

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