Is it OK for users to use either of a pair of replicated servers ?

[Adam Tauno Williams]

On Fri, 2013-02-01 at 10:01 +0000, John wrote:
> Hello, I have just set up a second server for a small email group and I 
> now have replication working between them. 

Great.

> I was very happy to note that it replicates both ways.

It does???  What version is this?

> My use-case is basically this: to have two servers, one acting as a 
> primary and another as a backup. The primary will be the one that goes 
> out to the internet to grab emails for users. Apart from that difference 
> the two servers are identical. Either can take on the primary role. 
> Users can connect their IMAP email clients to either server. One of the 
> pair runs sync_server and the other regularly connects to it to keep the 
> two servers in sync. It's a basic configuration intended for use by a 
> small number of people.

As far as I know that will not work.

> I'd like to confirm that the replication mechanism implemented with 
> sync_server and sync_client is ok for this kind of set-up. It certainly 
> appears to work just fine like this but I haven't found anything in the 
> documentation saying that two-way replication like this is ok (i.e. 
> where users can log in to either server).

I believe that multi-master is a feature for 2.5.x.