HP-UX Directory Server 8.1 deployment guide

appropriate for the environment. These basic scenarios can be combined to build the replication
topology that best suits the network environment.
• “Single-master replication”
• “Multi-master replication”
• “Cascading replication”
• “Mixed environments”
6.2.1 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. This is illustrated below.
Figure 6-1 Single-master replication
The supplier server can replicate a read-write replica to several consumer servers. The total
number of consumer servers that a single supplier server can manage depends on the speed of
the networks and the total number of entries that are modified on a daily basis. However, a
supplier server is capable of maintaining several consumer servers.
6.2.2 Multi-master replication
In a multi-master replication environment, master copies of the same information can exist on
multiple servers. This means that data can be updated simultaneously in different locations. The
changes that occur on each server are replicated to the other servers. This means that each server
functions as both a supplier and a consumer.
When the same data is modified on multiple servers, there is a conflict resolution procedure to
determine which change is kept. The Directory Server considers the valid change to be the most
recent one.
76 Designing the replication process