Sun Java System Web Server 7.0 supports session replication with some restrictions. The objective of session failover is to provide high availability to web applications. Session replication achieves this by replicating HTTP sessions from one instance to another server instance of the same cluster. So, each HTTP session has a backup copy on a remote instance. In the event of a failure which renders one instance in the cluster unavailable, the cluster still maintains session continuity.
However, the current version does not support the following features in session replication:
Simultaneous failures of any 2 or more instances. Also, the interval between 2 failures has to be greater than the time needed for a resurrected instance to fully recover.
Same session backup to more than one instance. In normal operation, there are only 2 copies of any session: the primary session and a backup session.
Session persistence. Sessions are only backed up in memory of another instance for the purpose of failover and not durable persistence.