Apache Karaf natively provides a failover mechanism. It uses a kind of master/slave topology where one instance is active and the others are in standby.
Karaf provides failover capability using either a simple lock file or a JDBC locking mechanism.
In both cases, a container-level lock system allows bundles to be preloaded into the slave Karaf instance in order to provide faster failover performance.
So, Talend ESB, based on Apache Karaf, benefits from those mechanisms.