Hello Jack
Setting up imapproxy on a third machine greatly improve
performances on my mailhub which doesn't refuse connexions
anymore.
Thanks a lot for your help !
Frank
Jack Stewart wrote:
Frank Bonnet wrote:
Timo Sirainen wrote:
On Thu, 2009-01-15 at 16:25 +0100, Frank Bonnet wrote:
I had to increase the max_mail_processes to 8192
to have a functionnal IMAP server with normal clients AND
squirrelmail clients
8192 sounds enormous to me , any infos welcome !
How many imap processes have you running typically?
Hi,
I don't know if this will help or not - I'm taking my comments offline
because it isn't clear if they are related to your core problem. Also,
they seem to be specific to high usage servers/people.
We're not 1.1.8 yet but I've spent a reasonable amount of time tweaking
the Linux side.
We run at about ~1300 processes per server.
Squirrelmail does a login/logout on every single page that is clicked.
So I've found that running an imap proxy (such as the one at
imapproxy.org really helps). It creates some additional connections but
they get re-used pretty frequently.
If 1.1.8 isn't logging out quickly, or not cleanly shutting down the
connection, or something similar, that could explain additional
connections. What does netstat -an show? On some O/S's the process will
disappear from ps but not be fully released until the socket/connection
disappears (in this case tcp). If you have a bunch of WAIT/FIN_WAIT's
something like this seems pretty likely.
I've found that going through localhost allows you to bypass TLS while
still enforcing TLS for non-localhost connections. It's pretty nice for
overhead/connect speed. Also, an imap proxy may need a non-encrypted
connection.
Besides the dovecot max_ ... settings, in our system you need to tweak
limits.conf and bump up the limits via the ulimit command in the dovecot
init script. Open file descriptors and process limits seem to be the
main settings.
After this, you get into kernel tuning such as inotify settings.
Let me know if you have any questions. If some of this helps, we might
want to feed it back into the list.
---Jack
