Red Hat DIRECTORY SERVER 8.1 - DEPLOYMENT Deployment Manual page 90

Chapter 6. Designing the Replication Process
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.
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. Consequently, to create a multi-
master environment between two supplier servers that share responsibility for the same data, create
more than one replication agreement.
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, create a range of replication agreements. Keep in mind that the four suppliers can be
configured in different topologies and that there are many variables that have a direct impact on the
topology selection.
Figure 6.3, "Multi-Master Replication Configuration A (Four Suppliers)"
illustrates a fully connected
mesh topology where all four supplier servers feed data to the other three supplier servers (which
also function as consumers). A total of twelve replication agreements exist between the four supplier
servers. This topology provides high server failure tolerance at the expense of high data dispersal for
every supplier.
80