master-master replication

[Michael Menge]

Hi,



Quoting Evgeniy Kononov via Info-cyrus <info-cyrus at lists.andrew.cmu.edu>:

> Hello!
>
> I have two servers with  
> cyrus-imapd cyrus-imapd-2.5.8-13.3.el7.centos.kolab_16.x86_64
> One server as master and second as replica.
> All worked fine when users login on master server, but when I  
> temporary move users on replica I found some trouble
> Messages synchronisation from replica to master goes fine if  
> sync_client sees a mismatch on the master, but if user create folder  
> on replica it isn't sync on master.
> Instead of it folder is unsubscribes from the master server and  
> removed from both server
>
> grep UNSUB maillog
> Sep 10 13:31:41 master sync_client[1456]: UNSUB user at example.com  
> example.com!user.user.foldername
>
> Why is it happend ?
> When I tried manual sync from replica to master server, folder was  
> subscribed. Is it possible that both servers will be master and  
> replica in same time.
>

Cyrus does not support master-master replication. Because of
CONDSTORE (https://tools.ietf.org/html/rfc4551) Cyrus is able
to handle messages on a master-master setup, but the information
about folder operations is not tracked and so cyrus is unable to
distinguish is a folder was subscribed on one server, or if a folder
was unsubscribed on the other. Same is true for folder
creation/rename/deletion

The master-master replication is a wanted feature but even the 3.0.x
does not support it. I am not sure about the upcoming 3.1.x or master
branch.


Regards,

    Michael



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