The image shows three computers in a Real Application Clusters environment. Each computer has its own local storage. They can also access a shared storage device. The shared storage contains raw devices for the OracleAS Metadata Repository.
The image also shows multiple computers running Oracle Identity Management services: Oracle Internet Directory, Oracle Directory Integration Platform, Oracle Application Server Single Sign-On, Oracle Delegated Administration Services, and OCA.
The image also shows multiple computers running Oracle Application Server middle tiers. The middle tiers communicate with the computers in the Real Application Clusters as well as with the computers running Oracle Identity Management services.