[Dovecot] problems with SSH-based clustering dovecot 2.1.1

[Michael Grimm]

Hi --

On 14.03.2012, at 15:09, Timo Sirainen wrote:
> On Wed, 2012-03-14 at 01:25 -0400, Michescu Andrei wrote:

>> The problem comes when I start using the master-master model: emails
>> starts getting duplicate with different ids.

> I was testing this a bit, and I guess in your tests dsync was running
> during a mail delivery, which seems to make it duplicate mails
> sometimes. I'll probably fix this at some point (I've actually been
> thinking about a larger dsync redesign),

Good to hear ;-)

> but anyway:
> 
> Even if dsync worked perfectly and didn't duplicate mails, it's not a
> great idea to do deliver mails randomly to both servers.

Sometimes croncobs are running on both servers at the same time 
producing locally delivered mails simultaneously, though. Ok, one 
can modify run times accordingly ...

> Better to give one MX a higher priority so mails typically are delivered
> through it.

That's what I did. Now dsync/replicator is performing great, if the 
mail volume is rather low. I'm very satisfied, because this is the
best performance ever. (Before I was running unison and dsync 2.0.)

But, whenever the high priority server will show delays during stress 
situations like huge mail loads, the low priority server will receive 
loads of mails as well. A dsync/replicator setup will then most probably 
produce duplicates (and multiples). That is a rather unrealistic 
scenario for my little severs, but others might have more difficulties.

And spammers don't care about mx priorities at all :-(

Regards,
Michael