[Dovecot] Solaris/SSLonly/Lots of Users

Chris Wakelin c.d.wakelin at reading.ac.uk
Wed Feb 21 17:40:31 UTC 2007

Steven F Siirila wrote:
> Anyone running Dovecot on Solaris, requiring only SSL connections, and
> servicing thousands of simultaneous users?  Our past attempts to do so
> have failed due to dovecot-auth using up all 256 of its file descriptors.
> I say 256 since we are limited to that by the 32-bit libraries.
> We are looking at either compiling Dovecot in 64-bit and letting dovecot-auth
> file descriptors accumulate (not ideal), or providing Timo with access to
> one of our test servers so he can debug the problem.  However, I would
> like to hear of anyone in the same boat first.  Thanks!

You don't need it to be 64-bit, just change the ulimit/plimit parameters
on the processes (try "man plimit"). You can change the default by
editing /etc/system


set rlim_fd_cur=2048
set rlim_fd_max=2048

to set the limit to 2048. We run "plimit -n 4096" on the dovecot master
process shortly after it starts and typically have 1200 or so concurrent
IMAP processes. Also look at "login_process_per_connection = no" in the
Dovecot configuration; this will mean the number of imap-login processes
is much reduced at the loss of a bit of security.

Best Wishes,

Christopher Wakelin,                           c.d.wakelin at reading.ac.uk
IT Services Centre, The University of Reading,  Tel: +44 (0)118 378 8439
Whiteknights, Reading, RG6 2AF, UK              Fax: +44 (0)118 975 3094

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