[Dovecot] Dovecot strong or not for a big Webmail architecture
Hello,
Do you think Dovecot could handle millions of active users in a big architecture ?
This cluster could be for example (each server is a bi quad Xeon 2.66 Ghz) :
- 40 Dovecot servers
- 4 LVS
- 20 Apache+PHP
- 2 Openldap
- 20 Postfix + ClamAV + SpamAssassin
- 1 NFS Netapps
For millions of user it could be multiple different clusters of 40 Dovecot servers with 1 Netapp for each cluster. I want to work in NFS. I've experimented problem with Cyrus and NFS on Netapp. I want to use maildir, I can manage limitations of inodes with Netapp.
I know webmail.us use Dovecot, what is the most big dovecot architecture known ? Do you think Dovecot can handle 1 million of active users in a good architecture ? Do you think it's a good solution to use one synchronised local Openldap on each server Dovecot ? Do you think It's possible to use Postgresql or MySQL instead of Openldap ? Are cyrus or courrier-imap better solutions ? Someone say "Zimbra is highly scalable and fast", I think Zimbra could be to heavy in this architecture, is Dovecot scalable ?
Thank you for your ideas.
Regards.
John Fistack
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On Thu, 2007-08-02 at 19:06 +0000, John fistack wrote:
For millions of user it could be multiple different clusters of 40 Dovecot servers with 1 Netapp for each cluster. I want to work in NFS.
You'll want to read at least http://wiki.dovecot.org/NFS. Dovecot v1.1 makes problems with attribute/data caches go away.
I know webmail.us use Dovecot, what is the most big dovecot architecture known ?
Portugal Telecom is the largest installation I know of. They use NFS + Netapps also.
Are cyrus or courrier-imap better solutions ?
Cyrus doesn't work properly with NFS and I don't think Courier has any advantages over Dovecot.
Hello,
On Thu, 2 Aug 2007 19:06:05 +0000 (GMT) John fistack john.fistack@yahoo.fr wrote:
Do you think Dovecot could handle millions of active users in a big architecture ?
Sure, but the architecture will play a bigger role than just Dovecot.
This cluster could be for example (each server is a bi quad Xeon 2.66 Ghz) :
- 40 Dovecot servers
- 4 LVS
- 20 Apache+PHP
- 2 Openldap
- 20 Postfix + ClamAV + SpamAssassin
- 1 NFS Netapps
I'm not sure where you are pulling these numbers from (but then again webmail is a lot more resource intensive than real mail clients). We are handling about 100k users with a total of 9 machines and one SAN backend. And yes, this includes all the components up there with Exim instead of Postfix. About 10-20% are using webmail. 6 machines are cluster pairs, 3 are MXs (no need for clustering there) and yes, any single machine can fail and things will still work, pretty much w/o noticeable performance impact, too. The whole thing is designed to be pretty much indefinitely scalable.
For historical reasons we stayed clear of NFS (this system architecture has been in production for 7 years, the last 3 with Dovecot), so I can not comment on that part from own experience. But I have a hard time imagining any single storage backend not melting from the traffic that these amounts of machines would generate (if they are actually needed). And even if the backend could handle it, the network towards it would be saturated a long time before those 40 Dovecot servers would run out of steam CPU wise.
Regards,
Christian
Christian Balzer Network/Systems Engineer NOC chibi@gol.com Global OnLine Japan/Fusion Network Services http://www.gol.com/
participants (3)
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Christian Balzer
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John fistack
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Timo Sirainen