[Dovecot] Mail replication ... totally confused !

[HL]

Hello,

I am totally confused configuring replication in dovecot.
In my case I have 2 servers
instead of running rsync as a daemon which takes a lot of time
I would like



SERVER-A will be the master
and
SERVER-B will be the slave

My users directly interact with server A,
Server B stands as a mails backup only

I've setup SERVER-B ( backup ) like that, NO SPECIAL CONF on master 
SERVER-A

Is this ok ??
I Don't want to miss any mails
Since this is a live server

   service aggregator {
        # give enough permissions for mail processes
        #
        fifo_listener replication-notify-fifo {
                user = vmail
                mode = 0600
        }
        unix_listener replication-notify {
                user = vmail
                mode = 0600
        }
   }
   service replicator {
        # start replication at startup
        #
        process_min_avail = 1
   }
   service doveadm {
        # if you're using a single virtual user, set this to start ssh 
as vmail
        # (not root)
        #
        user = vmail
  }
   service config {
        # needed to grant access to /var/run/dovecot/config for service 
doveadm
        #
        unix_listener config {
                user = vmail
        }
   }

 dsync_remote_cmd = ssh -p 1234 -l%{login} %{host} doveadm dsync-server 
-u%u -l%{lock_timeout} -n%{namespace}

plugin {
        mail_replica = remote:vm...@master-server-a.tld
        replication_full_sync_interval = 1 hours
   }