Red Hat DIRECTORY SERVER 7.1 - DEPLOYMENT Deployment Manual page 118

Common Replication Scenarios
Multiple servers can have master copies of the same data, but, within the scope of
a single replication agreement, there is only one supplier server and one
consumer. That means that to create a multi-master environment between two
supplier servers that share responsibility for the same data, you need to create
more than one replication agreement. Figure 6-2 shows the configuration for a
two-way multi-master replication.
Figure 6-2 Multi-Master Replication Configuration (Two Suppliers)
In the above illustration, supplier A and supplier B each hold a read-write replica
of the same data.
To create a multi-master environment between four supplier servers that share
responsibility for the same data, you need to create more than four replication
agreements. Figure 6-3 and Figure 6-4 illustrate two sample configurations of
four-way multi-master replication agreements. Keep in mind that the four
suppliers can be configured in different topologies and that there are many
parameters that have direct impact on the topology selection.
Figure 6-3 illustrates a fully connected mesh topology where all four supplier
servers feed data to the other three supplier servers (and to the consumer servers).
There are a total of twelve replication agreements among the four supplier
servers. This topology provides high server failure tolerance at the expense of
high fan-out for every supplier.
118 Red Hat Directory Server Deployment Guide • May 2005