Directory Server allows you to replicate directory data among as many server instances as necessary. Directory Server replication works as an LDAP extended operation that replays update operations from one server to another. The protocol for Directory Server replication is optimized to work quickly over the network. The protocol is also optimized to resolve conflicts when the same data is modified simultaneously on two different server instances.
The unit of Directory Server replication is the suffix. A replication agreement between two servers handles all the directory entries under a base entry in the directory information tree, such as dc=example,dc=com. Each agreement to replicate is set up point to point. On one hand, point to point agreements prevent replication from single points of failure when the network becomes partitioned. On the other hand, point to point agreements can be complex to manage as the number of replicas increases. Luckily, Directory Service Control Center handles much of the complexity for you. Directory Service Control Center allows you to manage groups of replicas that provide a common directory service.
You can configure timing, priority, and which data is replicated. You can also configure some servers, called masters, to accepts both updates and lookups. You can configure other servers, called consumers, to accept only lookups. In addition, you can publish update information over LDAP for client applications that must follow updates as they happen. For further explanation of replication, see Chapter 7, Directory Server Replication. For instructions on configuring replication, see Chapter 10, Directory Server Replication, in Oracle Fusion Middleware Administration Guide for Oracle Directory Server Enterprise Edition.