replication - more than 2 servers?
We tested dovecot for a fair amount of time and decided finally to put it into production under CentOS 7 (we are running 2.2.10). I just joined the list, so I apologize for what is probably a question that has been answered many times, but I was wondering if there are any plans to implement replication among 3 or more servers (all "masters", as with 2)? As best as I can tell, replication seems to be limited to 2 servers, and it is not obvious to me even how more than 2 would be supported syntactically in the configs. That is, what might be an example of the "mail_replica" clauses if such a thing was supported?
Am 16.12.2014 um 21:13 schrieb Ron Cleven:
We tested dovecot for a fair amount of time and decided finally to put it into production under CentOS 7 (we are running 2.2.10). I just joined the list, so I apologize for what is probably a question that has been answered many times, but I was wondering if there are any plans to implement replication among 3 or more servers (all "masters", as with 2)? As best as I can tell, replication seems to be limited to 2 servers, and it is not obvious to me even how more than 2 would be supported syntactically in the configs. That is, what might be an example of the "mail_replica" clauses if such a thing was supported?
if you *really* have that large number of users and load you should split them to different servers (replicated server pairs) because you end in replication overhead eating away all the benefits otherwise
master-master replication independent of the software is somehow limited by phyiscs (delays, replication traffic, replication I/O) and can't scale endless
Dovecot replication will never scale until it implements some form of token ring topology where data is sharded. You should look at obox plugin for dovecot and some form of S3 compatible storage that can be available in multiple data centers. We are using (pithos.io) and the Cassandra database to backend a test cluster with good results between two data centers. This could potentially scale infinitely if that's what you need.
On Dec 16, 2014, at 2:39 PM, Reindl Harald h.reindl@thelounge.net wrote:
Am 16.12.2014 um 21:13 schrieb Ron Cleven: We tested dovecot for a fair amount of time and decided finally to put it into production under CentOS 7 (we are running 2.2.10). I just joined the list, so I apologize for what is probably a question that has been answered many times, but I was wondering if there are any plans to implement replication among 3 or more servers (all "masters", as with 2)? As best as I can tell, replication seems to be limited to 2 servers, and it is not obvious to me even how more than 2 would be supported syntactically in the configs. That is, what might be an example of the "mail_replica" clauses if such a thing was supported?
if you *really* have that large number of users and load you should split them to different servers (replicated server pairs) because you end in replication overhead eating away all the benefits otherwise
master-master replication independent of the software is somehow limited by phyiscs (delays, replication traffic, replication I/O) and can't scale endless
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Reindl Harald
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Ron Cleven