On Tue, 2006-06-27 at 14:49 +0200, Marten Lehmann wrote: > Hello, > > > Just out of curiosity, what kind of performance problems at what load do > > you have. It was claimed that dovecot is really fast and we plan to > > evaluate it in the near future for some projects so any hints where to > > dig are welcome. > > the difference is, that cyrus handles a lot of things while the mail is > being delivered, which saves a lot of time. We had to split the incoming > mailserver (smtp) and the pop3/imap server because one server couldn't > handle the load any longer. > > Example delivery with exim+dovecot: > To check the quota, exim has to count all messages (files) in all > directories in the maildir (very timeconsuming with NFS mounted maildirs). > Then the message is delivered to maildir/tmp and moved to maildir/new > (another two NFS operations). > When a user is connecting to IMAP now, dovecot has to look through all > directories within the maildir of files or gone, new ones appeared and > build the cache and index accordingly. This is done locally on the disk, > so it is a bit faster, but it is time consuming on big maildirs anyway. > Now dovecot can start serving the new message. > > Example delivery with exim+cyrus: > Exim sends to message to cyrus via unix socket or tcp socket. The rest > is done locally on the cyrus backend server: > Checking for quota > Updating indizes > Possibly notifying an existing imap-connection about the new message > So the delivery is very fast, because cyrus doesn't have to look through > all messages to check the quota: It can be looked up in the index. > When the user is connecting to IMAP, the index is already prepared, > cyrus doesn't have to look for changes in the maildir at this stage so > it can serve the new message immediately. > > In small setups with everything on one server, exim (or any other mta) + > dovecot should work fine, while cyrus is maybe a bit more complicated to > setup. But with bigger setups (or expected growth in the future) cyrus > and its option of cyrus murder should scale better. > > Regards > Marten Although the comparison below includes a commercial imap server, it does give a good comparison between Cyrus and other open source imap servers. http://www.isode.com/whitepapers/mbox-benchmark.html Murray ---- Cyrus Home Page: http://asg.web.cmu.edu/cyrus Cyrus Wiki/FAQ: http://cyruswiki.andrew.cmu.edu List Archives/Info: http://asg.web.cmu.edu/cyrus/mailing-list.html
