hardware for cyrus murder

Thomas Hager duke at sigsegv.at
Tue Nov 11 05:02:09 EST 2003

On Mon, 2003-11-10 at 18:19, Giridhar Raichur wrote:
> We are in the process of converting UW Imap to Cyrus Imap. We have about
> 10K users using about 100K mailboxes. We anticipate the number of users
> to increase to 15K.
> I looked at http://asg.web.cmu.edu/cyrus/ocnfig.html that describes
> Cyrus Configuration for murder hardware. What is not clear to me is the
> basis for determining the number of frontend servers and backend
> servers. I would appreciate any help or pointers to additional
> documentation.
well, the number of mailboxes should not be of any concern, the expected
load is the key.

on one site i had a cyrus imapd running with >700k users on a single
server without any stability problems. well, i had no load on that
machine at all.

on another site i'm running a cyrus murder with 2 frontends and 2
backends handling about 30k users. we have ldap daemons on the backend
used for user authentication/mail routing and mtas on the frontends
handling smtp.
this system handles an average of 8 pop3/imap4 logins per second and
4000 lmtp deliveries per hour. 
but it reaches its limits in very busy hours. usually the cyrus internal
authentication begins to fail. backends and mupdate slaves can no longer
authenticate to the mupdate master and frontend services fail to
authenticate to the locally running mupdate slaves.

we are scaling now by moving the mtas to dedicated servers and by
removing the mail routing load from the backend ldap daemons.


Thomas "Duke" Hager                       {duke,hager}@sigsegv.at
GPG: 1024D/D27F858C            http://www.sigsegv.at/gpg/duke.gpg
"Never Underestimate the Power of Stupid People in Large Groups."

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