Having done quite a bit with MySQL's replication in a master-master scenario, dragons be here. It works if you know exactly what your application will be doing,

Having done quite a bit with MySQL's replication in a master-master scenario, dragons be here. It works if you know exactly what your application will be doing, but honestly, it's best to avoid it. Master-master replication is tricky with any system, but the particular implementation of MySQL's replication semantics make it even more prone to inconsistent data.