Basic Replication Concepts

The replication mechanism is described in detail in Chapter 7, Directory Server Replication, in Oracle Fusion Middleware Reference for Oracle Directory Server Enterprise Edition. The following section provides basic information that you need to understand before reviewing the sample topologies described later in this chapter.

Master, Consumer, and Hub Replicas

A database that participates in replication is defined as a replica.

Directory Server distinguishes between three kinds of replicas:

• Master or read-write replica. A read-write database that contains a master copy of the directory data. A master replica can process update requests from directory clients. A topology that contains more than one master is called a multi-master topology.

• Consumer replica. A read-only database that contains a copy of the information in the master replica. A consumer replica can process search requests from directory clients but refers update requests to master replicas.

• Hub replica. A read-only database (like a consumer replica) that is stored on a Directory Server that supplies one or more consumer replicas.

The following figure illustrates the role of each of these replicas in a replication topology.

Figure 10–1 Role of Replicas in a Replication Topology

The previous figure is for illustration purposes only and is not necessarily a recommended topology. Directory Server supports an unlimited number of masters in a multi-master topology. A master-only topology is recommended in most cases.