dovecot and glusterfs

[Nick Edwards]

On 1/13/15, Michael Schwartzkopff <ms at sys4.de> wrote:
> Hi,
>
> I did some experiments with dovecot on a glusterfs on the active nodes
> without
> a director. So I had concurrent access to the files.
>
> With the help of the available documentation about NFS and fcntl locks I
> managed to find out the following:
>
> With the plain mbox format dovecot seems to apply and to honor the fcntl
> locks.  But since this format is not used any more in real setups, it is
> useless.
>
> With mdbox and maildir format I could reliably crash my mail storage just by
>
> delivering mails to the both dovecots via LMTP to the same user. In maildir
>
> dovecot seems not the set / respect the fnctl locks of the index file.
> dotlocks
> do not seems to work either with mdbox.
>
> So I think the only solution os to use a director in a real world setup. Or
> is
> there any non-obvious trick that I did not check?

Interesting, we use NFSv3 dovecot LDA with maildir, we have at present
two dozen front end SMTP servers (using dovecot-lda) and some, hrmm we
added a few more over Christmas, so I think about 32  pop3 servers,
but with only 4 imap servers incl webmail (IMAP is not heavily used
here due to government spy laws) talking to NAS storage server
backend, *we do not use director* at all and has never been an issue.
Director IIRC solves the problem of IMAP inconsistency, but we never
see advantage when we tested, no doubt it solves some fancy setup
problem, but since director can not help with pop3, it was not worth
the hassle. never had any problems with webmail either, load balancers
seem to look after it well

We did see  lot of people with issues with LMTP, but we never saw
these with lda.

> I think it would be really nice if dovecot could use glusterfs for realy
> scalable postbox servers.

There was some nasty problems with that with cyrus, so much so, most
uni's here who used that moved to a  NAS backend and no one has
whinged since :->