[Dovecot] Concurrent dovecot instances on same spool?

[Timo Sirainen]

On Thu, 2012-03-01 at 09:21 +0100, Jacek Osiecki wrote:

> I am setting up an high-availability server set, which consists of two (or 
> more) servers with common disk space, all set behind redundant hardware 
> load balancers. At first, there will be two servers and disk space will be 
> kept on NFS server or on both servers using DRBD+OCFS2 filesystem (what
> creates kind of networked RAID1 storage space). This will be done mostly 
> to keep WWW service available in case when one of servers fails.
> 
> However, if we have everything redundant, why not have the same with SMTP 
> and POP3/IMAP? But - won't anything fail if two (or more) dovecots are 
> accessing the same disk space, both for IMAP/POP3 and LDA/LMTP?

If both servers randomly access users' mails, with NFS you'll have some
trouble, with OCFS2 probably less trouble. But in both cases you'll have
better performance and no problems if you use Dovecot director in both
servers (install both director and backend to both servers).
http://wiki2.dovecot.org/Director