HIGHESTMODSEQ replication issue

[Gustavo Ajeitos [Office365]]

Hi John,

     Thank you for your answer!

I agree with you, I think you recommendation should solve the problem, 
it seems the only possible workaround.
I have to investigate if it possible and how to accomplish that with the 
load balancer.

Gustavo

El 3/11/20 a las 15:27, John Fawcett escribió:
> On 09/10/2020 21:17, Gustavo Ajeitos [Office365] wrote:
>> Hello,
>>
>> I'm using dovecot 2.3.10 in OpenSUSE and I have configured a
>> master/master replication between two backends, it works well but I
>> have found an issue with the replication of the HIGHESTMODSEQ.
>> When I move a set of message from a mailbox to other, e.g. move 3
>> messages from INBOX to Junk, the HIGHESTMODSEQ get different on each
>> server, with no errors in the log:
>>
>> [Borrador] 34:34
>> [Sent] 63:63
>> [Drafts] 12:12
>> [Trash] 146:146
>> [Junk] 219:218
>> [INBOX] 1133:1130
>>
>> It can be fixed executing a full sync:
>> $ sudo doveadm -D -v sync -u user at test.priv -d -l 30 -U
>>
>> But it is not a solution because it happens all the time that a user
>> move messages.
>>
>> I'm using ActiveSync and the ActiveSync server use the HIGHESTMODSEQ
>> as part of the synchronization key (sync_key), so in that situation
>> the server detect changes on the mailbox if it connects to the backend
>> with a different HIGHESTMODSEQ that it previously cached, causing a
>> loop beetween the ActiveSync server and the the email client, where
>> the server constantly inform email client about nonexistent changes.
>>
>> Could it be a bug in Dovecot replication? How can I solve it?
>>
>> Best regards,
>> Gustavo Ajeitos
>>
> Hi Gustavo
>
> I don't know if this is a bug, but one thing I noticed is that for
> master/master replication the recommendation is to have specific users
> always directed to the same server. If you implemented this
> recommendation for the ActiveSync connections, would that solve the problem?
>
> John
>