[Dovecot] Concurrent dovecot instances on same spool?

[Timo Sirainen]

On 5.3.2012, at 19.25, Jacek Osiecki wrote:

>>> 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
> 
> Thanks, I'll probably give it a try. On the other hand, it would be nice to have a possibility to allow multiple dovecot instances to access mail spool (at cost of handling some extra file/directory locks) - a bit slower, but safe...

You can safely do that with director.

Also the problem with NFS isn't locks, but caching.

> Another question: as I assume, when you wrote about troubles it was applying to IMAP. How about LMTP/LDA? Can anything bad happen when one mailbox is being filled by LMTP/LDA from more than one server)?

Yes, because they're still updating Dovecot index files. You could disable LMTP/LDA index updates, but I'm still not sure if it works 100% correctly (because dovecot-uidlist is appended to).