Netscape NETSCAPE DIRECTORY SERVER 6.1 - ADMINISTRATOR, Administrator'S Manual

Page: 491 / 578

Replication and the Attribute Uniqueness Plug-In
Chapter 17 Using the Attribute Uniqueness Plug-In 491
Replication and the Attribute Uniqueness Plug-In
When you use the attribute uniqueness plug-ins on Directory Servers involved in a
replication agreement, you must think carefully about how to configure the plug-in
on each server.
Consider the following cases:
• Simple replication with one supplier and one or several consumers
• Complex replication with multiple masters
Attribute uniqueness plug-ins do not perform any checking on attribute values
when an update is performed as part of a replication operation.
Simple Replication Scenario
Because all modifications by client applications are performed on the supplier
server, the attribute uniqueness plug-in should be enabled on the supplier. It is
unnecessary to enable it on the consumer server.
Enabling the attribute uniqueness plug-in on the consumer will not prevent
Directory Server from operating correctly, but is likely to cause a performance
degradation.
Multi-Master Replication Scenario
In a multi-master replication scenario, the two masters act both as suppliers and
consumers of the same replica. Because multi-master replication uses a loosely
consistent replication model, enabling an attribute uniqueness plug-in on one of
the servers is not sufficient to ensure that attribute values will be unique across
both masters at any given time. Therefore, enabling an attribute uniqueness
plug-in on one server can cause inconsistencies in the data held on each replica.
However, you can use an attribute uniqueness plug-in, providing all of the
following conditions are met:
• The attribute on which you are performing the uniqueness check is a naming
attribute
• The attribute uniqueness plug-in is enabled on both masters