There are two main types of high availability solutions that you can use with the Oracle Application Server Infrastructure:
Cold Failover Clusters: In this solution, the infrastructure is installed on a set of disks that is shared by two or more nodes in a hardware cluster. If the active node in the cluster fails, another node is brought online. Only one node is active at a time. This solution requires the use of clusterware.
Active Failover Clusters: This is a limited release feature in Oracle Application Server 10g (9.0.4). This solution allows the infrastructure to run in an active/active configuration. The infrastructure database is installed as a Real Application Cluster database. All other infrastructure processes are installed on each node of the hardware cluster. A load balancer is deployed in front of the Active Failover Cluster. This solution ensures the highest infrastructure availability. When one node of the cluster fails, all incoming requests are immediately diverted to one of the available nodes of the cluster.