Any DS server may hold a copy of a user-defined replica. Changes to a user-defined partition must be distributed to other servers that hold a copy of the same user-defined partition.
When these changes occur, they are replicated under the control of the EDirectory Synchronization Process.
A Edirectory Replica is a copy of a user-defined partition that is placed on an NDS server.
There is no limit to how many Edirectory Replicas a server can hold, subject to disk space availability.
Only one replica of the same user-defined partition can exist on a server.