There exists a variety of ready to use mechanisms and practices to achieve redundancy with FUSE ESB. I've collected a few references below to start your readings. I believe the failover documentation will be of most interest to you. I would recommend using the JDBC failover architecture as you probably want to use multiple nodes for your setup. As a note, by adjusting the start level in the systems.properties file you can achieve various levels of 'hot standby' for your slave instances, which can dramatically improve their performance in coming to full service in the event of a master node going offline.
Configuring Failover Deployments:
Setting up Servicemix 4 with H.A. in mind:
Adding Container Level Locking to your H.A. Servicemix 4 deployment:
Setting up SMX4 failover with MySQL: