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Common Replication Scenarios
In the case of multi-master replication, the replicas on each master are said to be
loosely consistent because at any given time, there can be differences in the data
stored on each master. This is true even when you have selected to always keep
replicas in sync, because:
•
There is a latency in the propagation of update operations between masters,
and suppliers.
•
The master that serviced the update operation does not wait for the second
master to validate it before returning an "operation successful" message to the
client.
Common Replication Scenarios
You need to decide how the updates flow from server to server and how the
servers interact when propagating updates. There are three basic scenarios:
•
Single-Master Replication
•
Multi-Master Replication
•
Cascading Replication
•
Mixed Environments
The following sections describe these methods and provide strategies for deciding
the method is appropriate for your environment. You can also combine these basic
scenarios to build the replication topology that best suits your needs.
Single-Master Replication
In the most basic replication configuration, a supplier server copies a replica
directly to one or more consumer servers. In this configuration, all directory
modifications occur on the read-write replica on the supplier server, and the
consumer servers contain read-only replicas of the data.
The supplier server must perform all modifications to the read-write replicas
stored on the consumer servers. Figure 6-1 on page 101 shows this simple
configuration.
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Netscape Directory Server Deployment Guide • May 2002
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