[Dovecot] Hints for a NFS-Setup

[Timo Sirainen]

On Fri, 2012-03-30 at 21:37 +0200, Patrick Westenberg wrote:
> Nick Warr schrieb:
> 
> > I think some of the new Dovecot (director?) software is user aware, but
> > I don't know if it's quite ready for production.
> 
> Yes, with director it should be something like that:
> 
> MTA --(lmtp)--\               /--(lmtp)--> backend1 --\
>                  -- director --                         -- NFS
> MTA --(lmtp)--/               \--(lmtp)--> backend2 --/
> 
> 
> IMAP-User --> frontend1 --\              /--(imap)--> backend1 --\
>                             -- director --                         -- NFS
> IMAP-User --> frontend2 --/              \--(imap)--> backend2 --/

The director above must be the same one for both IMAP and MTA.

> So what happens if user1 at example.tld receives a mail?
> 
> - The director decides to connect to backend1 which in turn stores
> the mail on the NFS share and the index file locally?
> 
> - Then, user1 at example.tld connects to one of the frontends. Does the 
> director know that, earlier, this user received a mail and proxies him
> to backend1 too?

Yes. Director process actually doesn't know anything about mail
protocols, it simply does username -> backend mapping. The regular
Dovecot IMAP/POP3/LMTP/doveadm proxying code handles the rest.