I'm just preparing to build a new mail server for use at an ISP handling over 10,000 mailboxes and several domains.
We're currently using Qmail, but we'd like to move away from that since we have now changed our inbound mail systems over to Postfix.
Postfix will be receiving the mail, and I'm trying to decide between Dovecot and Cyrus-Imapd for the POP & IMAP service.
Does anybody have any advice or opinions about which of these two packages would be better for a large installation. I'd prefer if the package could tie into MySQL for user authentication, and all mailboxes will be virtual in the sense that they won't have local system accounts.
Thanks for your help. Bob.
On Fri, 2006-24-03 at 17:14 -0600, Bob Pierce wrote:
I've read on numerous occasions that Cyrus-Imapd will scale better than Dovecot. I have have not, however, read any hard numbers comparing performance between the two. Yeah, that was useless. :)
I love Dovecot because it's incredibly easy to setup and maintain. I personally haven't had to roll it out to large sites yet, so I've stuck with it. Also, it's been handling email boxes with several hundred megabytes of email with ease. A lot of that great performance is coming from the Maildir setup I use, I'm sure.
Anyway, either one of them might work for you. It really depends on how the system would be used, the type of hardware it's going to be installed on, etc. I suggest you try out both - for 10,000 users, you'll HAVE to do a lot of testing anyway.
Regards,
Ranbir
Les Mikesell wrote:
Cyrus is designed for exactly that kind of environment and should give the best performance.
But on the other hand cyrus is outside the scope of included packages for Centos and will have to managed differently when dealing with updates. Not to say it's bad or good, just something to consider when accounting for sysadmin tasks and effort.
when when email users aren't system users, even dovecot would have to be managed differently.
Which is why postfix with db support is included in centosplus.
-- "They that can give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety'' Benjamin Franklin 1775
I have seen some instances where Dovecot stops responding on high end servers.
I've also seen systems where Cyrus gobbles up resources when mailboxes get large, to such an extent it cripples the machine.
My preference is Dovecot, it is very easy to setup and maintain.
I might be wrong here but I thought Cyrus has a user base separate to the Unix accounts, which is either a PITA or a blessing depending on what you want. My experience is this would be a PITA but for 10,000 users this could be beneficial...
In each case I would stick with Dovecot...
P.
Jim Perrin wrote:
Peter Farrow wrote:
I'm a sucker for the classics....still running UW IMAP. 8-) A few weeks ago I had folks review the latest/greatest out there for a mid-sized company with a few hundred accounts. They came back with Cyrus. I asked if anyone had looked into dovecot and eyes glazed over. So I pointed them at Johnny's dovecot/postfix page and asked that they include that in the mix (we've been using postfix since the 90's) and after a few hours the group enthusiastically recommended dovecot. Either dovecot has lots of advantages for our environment...or it's just close to bonus time. Hopefully, it was the former. 8-) So we'll be switching over "real soon now."
Cheers,
On Fri, 2006-03-24 at 17:14 -0600, Bob Pierce wrote:
----- personally, I would use cyrus - in fact, on that scale, I think you would be making a mistake not to use cyrus or courier.
I would also use LDAP and not mysql as LDAP scales to multiple systems in case you actually try to do more sophisticated things such as multiple data stores on different systems and integrating into CentOS for things like Postfix is simple whereas you are going to have to get or do a rebuild to make it work with MySQL.
LDAP, cyrus-imapd and postfix are a perfect combination for virtual users...MySQL is a bad idea.
Craig
Craig White wrote:
I agree too, And sometimes, MySQL "hang" because the number of simultaneous connexions is limited (you can increase them but for 10000 accounts you will have some problems). It's a far better idea to use LDAP .. with Cyrus-imap of course. And last thing: a server with high performances in read/write ... We install cyrus-imap on a Proliant without write cache (you need a battery to activate it): big mistake !
On Mon, 27 Mar 2006 08:29:48 +0400 jean-sebastien Hubert security@air-austral.com wrote:
I have a cyrus setup with 300k accounts and I dumped ldap for mysql because it's performance and reliability were just horrible. But that was four years ago :)
Never expirienced that and it's doing 2k queries per second 24/7 for the last four years.
Yup, an old dual p3 box is bored while serving those 300k accounts ... fast i/o is everything when doing mail serving. That either means plenty (50+) 15k rpm disks in jbod/raid10 or a big (as much as possible) battery-backed write cache. Figure out what is cheaper for you.
On Mon, 2006-03-27 at 22:23 +0200, Jure Pečar wrote:
---- Any db is only as effective as the administrator and the the design of the system permits. It's likely that your skills with mysql are well honed and your skills with LDAP were lacking. LDAP is a decidedly different beast than an sql db.
Performance issues can usually be fixed...scalability issues cannot be fixed if the system doesn't permit. Replication of an LDAP system is easily accomplished, clearly not the case for mysql.
Craig
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Bob Pierce -
Chris Mauritz -
Craig White -
jean-sebastien Hubert -
Jim Perrin -
Jure Pečar -
Kanwar Ranbir Sandhu -
Keith Morse -
Les Mikesell -
Peter Farrow