Performance problems, compared to wu-imapd

Paul M Fleming pfleming at
Thu Jan 29 10:22:55 EST 2004

Comments are based on Cyrus and wu-imap using mbx format -- 

Just reading mailboxes isn't a good test.. Cyrus _really_ excels when
you start do a lot of things to the same mailbox at the same time. For
example, deleting email and delivering new email to the same mailbox at
the same time. Try putting several thousands messages in a mailbox and
doing concurrent searches, fetches and delivers to the same mailbox.
Deleting on wu-imapd is brutal in mbx format because the entire file
must be rewritten. We support 2-3k accounts in a small cluster and
maintain 150-200 concurrent connections per server with a load average
of 0. The machines are single 1Ghz PIII w/ 1GB of RAM and hardware RAID
5 w/ 4 - 36GB drives. Also, your selection of database format can affect
load/performance. Are you using skiplist of the mailbox db? 

pheonix1t wrote:
> Tuomas Toropainen wrote:
> >I have been running some performance tests on my cyrus test installation.
> >The computer is not very fast, but my intention was just try how cyrus
> >performs compared to wu-imap on the same computer. It's 350Mhz P2 with
> >256MB memory and 4,5GB scsi disk. OS is redhat 9 and filesystem ext3. I'm
> >using mozilla mstone as benchmark program, and also when it has been
> >running, I have used squirrelmail to see how slow the imap service gets.
> >Mstone and squirrelmail are being run on other computers.
> >
> >The problem is that wu-imapd seems to perform much better than cyrus.
> >Cyrus version is 2.1.16, compiled with default database options. Syslog is
> >not logging debug messages, and has synchronous logging disabled (-). Both
> >systems have 500 test users, about 100 mails per user in INBOX. Mails are
> >generated with postal and are random text, max 20kB size. I also tried
> >with 100 users, the results are much same. Mstone results, squirrelmail
> >speed and computer load all tell that wu-imapd is faster.
> >
> >For example, with 500 users, using cyrus mstone managed to retrieve 8,730
> >messages during 5 minute test, averaging 652.70ms per message. But using
> >wu-imapd, 33,709 messages were retrieved, averaging 15.71ms per message.
> >Maximum concurrent connections was a little lower with wu-imapd (~180 vs
> >220), but with cyrus computer load increased to 150 when there were 190
> >imapd processes. Wu-imapd caused a maximum load of ~15.
> >
> >What am I doing wrong, or is this computer just too slow for cyrus to
> >perform well? Or are the default databases so poor that they cayse this?
> >
> >Complete results are at
> > (cyrus)
> >and (wu-imapd)
> >
> >Thank you for any help :)
> >
> >
> >
> >
> I didn't measure performance, but I recently upgraded a client's mail
> server from uw-imap to cyrus.  They had about 2gb of mail.  I was using
> the mbx mailbox format on uw-imap.  The performance on searching on
> uw-imap was getting very slow.  After I migrated the mail server to
> cyrus/postfix the performance improved drastically.  This was on a
> proliant 800 server, 550MHZ, 256RAM, 4 scsi disks.....
> When I originally set them up, I didn't think their emails would get
> that big......generally for large mail servers, cyrus or courier is the
> preferred method.

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