The Directory role identifies a Security Center system. It manages all entity configurations and system wide settings.
Only a single instance of this role is permitted on your system. The server hosting the Directory role is called the main server, and must be set up first. All other servers you add in Security Center are called expansion servers, and must connect to the main server to be part of the same system.
Because the Directory role is responsible for the authentication of all client connections, it cannot be configured in the Config Tool client application. To configure the Directory role, you must log on to Server Admin from a web browser.
In a multiple Directory server configuration, Directory failover and load balancing is managed by the Directory Manager role.