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Introduction to Replication
•
Fault tolerance/Failover — By replicating directory trees to multiple servers,
you can ensure your directory is available even if some hardware, software,
or network problem prevents your directory client applications from
accessing a particular Directory Server. Your clients are referred to another
Directory Server for read and write operations. Note that, to support write
failover, you must have a multi-master replication environment.
•
Load balancing — By replicating your directory tree across servers, you can
reduce the access load on any given machine, thereby improving server
response time.
•
Higher performance and reduced response times — By replicating directory
entries to a location close to your users, you can vastly improve directory
response times.
•
Local data management — Replication allows you to own and manage data
locally while sharing it with other Directory Servers across your enterprise.
Before defining a replication strategy for your directory information, you should
understand how replication works. This section describes:
•
Replication Concepts
•
Data Consistency
Replication Concepts
When you consider replication, you always start by making the following
fundamental decisions:
•
What information you want to replicate.
•
Which server (or servers) holds the master copy, or read-write replica, of that
information.
•
Which server (or servers) holds the read-only copy, or read-only replica, of
the information.
•
What should happen when a read-only replica receives an update request;
that is, to which server should it refer the request.
These decisions cannot be made effectively without an understanding of how the
Directory Server handles these concepts. For example, when you decide what
information you want to replicate, you need to know what is the smallest
replication unit that the Directory Server can handle. The following sections
contain definitions of concepts used by the Directory Server. This provides a
framework for thinking about the global decisions you need to make.
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Netscape Directory Server Deployment Guide • October 2004
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