Designing The Replication Process; Introduction To Replication - Red Hat DIRECTORY SERVER 8.1 - DEPLOYMENT Deployment Manual

Chapter 6.

Designing the Replication Process

Replicating the directory contents increases the availability and performance of the directory service.
Chapter 4, Designing the Directory Tree
the design of the directory tree and the directory topology. This chapter addresses the physical
and geographical location of the data and, specifically, how to use replication to ensure the data is
available when and where it is needed.
This chapter discusses uses for replication and offers advice on designing a replication strategy for the
directory environment.

6.1. Introduction to Replication

Replication is the mechanism that automatically copies directory data from one Red Hat Directory
Server to another. Using replication, any directory tree or subtree (stored in its own database) can
be copied between servers. The Directory Server that holds the master copy of the information
automatically copies any updates to all replicas.
Replication provides a high-availability directory service and can distribute the data geographically. In
practical terms, replication provides the following benefits:
• Fault tolerance and failover — By replicating directory trees to multiple servers, the directory service
is available even if hardware, software, or network problems prevent the directory client applications
from accessing a particular Directory Server. Clients are referred to another Directory Server for
read and write operations.
NOTE
Write failover is only possible with multi-master replication.
• Load balancing — Replicating the directory tree across servers reduces the access load on any
given machine, thereby improving server response time.
• Higher performance and reduced response times — Replicating directory entries to a location close
to users significantly improves directory response times.
• Local data management — Replication allows information to be owned and managed locally while
sharing it with other Directory Servers across the enterprise.
6.1.1. Replication Concepts
Always start planning replication by making the following fundamental decisions:
• What information to replicate.
• Which servers hold the master copy, or read-write replica, of that information.
• Which servers hold the read-only copy, or read-only replica, of that information.
• What should happen when a read-only replica receives an update request; that is, to which server it
should refer the request.
Chapter 5, Designing the Directory Topology
and cover
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