Chapter 8.

Managing Replication

Replication is the mechanism by which directory data is automatically copied from one Red Hat Directory Server instance to another; it is an important mechanism for extending the directory service beyond a single server configuration. This chapter describes the tasks to be performed on the master and consumer servers to set up single-master replication, multi-master replication, and cascading replication.

1. Replication Overview

Replication is the mechanism by which directory data is automatically copied from one Directory Server to another. Updates of any kind — entry additions, modifications, or even deletions — are automatically mirrored to other Directory Servers using replication. This section contains information on the following replication concepts:

Section 1.1, “What Directory Units Are Replicated”

Section 1.2, “Read-Write and Read-Only Replicas”

Section 1.3, “Suppliers and Consumers”

Section 1.4, “Changelog”

Section 1.5, “Replication Identity”

Section 1.6, “Replication Agreement”

Section 1.7, “Compatibility with Earlier Versions of Directory Server”

1.1. What Directory Units Are Replicated

The smallest unit of of the directory which can be replicated is a database. This means that one can replicate an entire database but not a subtree within a database. Therefore, when creating the directory tree, consider any replication plans as part of determining how to distribute information.

Replication also requires that one database correspond to one suffix. This means that a suffix (or namespace) that is distributed over two or more databases using custom distribution logic cannot be replicated. For more information on this topic, see Section 2, “Creating and Maintaining Databases”.

1.2. Read-Write and Read-Only Replicas

A database that participates in replication is called a replica. There are two kinds of replicas: read-write or read-only. A read-write replica contains master copies of directory information and can be updated. A read-only replica services read, search, and compare requests, but refers all update operations to read-write replicas. A server can hold any number of read-only or

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HP UX Red Hat Direry Server Software manual Replication Overview, What Directory Units Are Replicated