This figure shows two tiers of nodes:
In one tier, you have two nodes running Oracle Delegated Administration Services and OracleAS Single Sign-On. Each node has its own local storage device on which you install the Oracle home for Oracle Identity Management (in this case, Oracle Delegated Administration Services and OracleAS Single Sign-On components).
Both these nodes are active. There is a load balancer to direct requests to both nodes.
A firewall separates this tier from the next tier.
In the second tier, you have two nodes (one active and one passive) and a shared storage device. OracleAS Infrastructure is installed on the shared storage. The oraInventory directory is also on the shared storage.
The virtual hostname and IP address are associated with the active node. The active node has access to the shared storage.
The active node runs OracleAS Metadata Repository, Oracle Internet Directory, and Oracle Directory Integration Platform.
If node 1 fails, node 2 takes over. It gets access to the shared storage, becomes associated with the virtual hostname and IP address, and runs the Oracle Application Server processes.