The Sun Cluster HA for Sun Java System Application Server makes the transactions highly available. When a node running an instance of the Sun Java System Application Server crashes, transactions are lost unless they are recovered by other running instances, running on a different node. Transactions can also be recovered by restarting the crashed server instance on the same node or on a different node. Because the Node Agents are configured as a failover data service, the data service fails over the crashed instances to other Sun Cluster nodes so that when the server is starting up on a new Sun Cluster node the transactions are recovered.