Master-master replication means that both servers could act as a master and take write traffic. Do you intend to set them up with one server being active and another being passive? You said you have failed over once, so is the application actively writing/reading to the database now? If that is the case, several things you could do
- use the application’s connection parameter to connect to the master, and run “show variables like ‘hostname’;”
- or just by checking the connected users and the traffic on each host via “show processlist”.
- or run “show master status” to check which server’s binlog file is rolling forward.
Regarding SHOW SLAVE STATUS, if a server is not a slave of any server, the command would return an empty set, otherwise, the output would tell the master(Master_host), whether the replication is in action (Slave_IO_Running, Slave_SQL_Running), the master binlog position that slave is currently replicating and so.
The manual would be a great resource to learn about replication. http://dev.mysql.com/doc/refman/5.6/en/replication.html