On 30.3.2012, at 15.38, Nick Warr wrote:
As far as I understood I will get poor performance if I'd just switch from OCFS2 to NFS (while keeping this configuration) with 4 hosts accessing the NFS-share and the index files on it and it is recommended to assign users to a specific host (http://wiki2.dovecot.org/NFS).
I'm uncertain what's the meaning of "user" in this context. Is it an IMAP-User or every incoming mail?
IMAP, POP3, LDA so everything.
If you've got a load balancer, it should be fairly easy to do simple IP stickiness, with a long enough timeout, most IMAP and POP3 users will stay on the same server.. I'm sure there is some load balancing software that's also L7 aware, and could direct by username (though you'd probably have to have the LB terminate the SSL, not the server behind it).
IP stickiness isn't enough if user uses more than one IMAP client, which is pretty common nowadays. And doesn't help at all with LDA.
I think some of the new Dovecot (director?) software is user aware, but I don't know if it's quite ready for production.
Anything else except Dovecot director will cause corruption with NFS. Several really large sites already use director in production.