Purpose

Replicas are created for two reasons:

• Directory Fault Tolerance. If a hard disk crashes or a server goes down, a replica on another server can still authenticate users to the network and provide information about Directory objects.

  With the same information distributed on several servers, you are not dependent on any single server being up to authenticate you to the network or to provide services to you.

  You can store more than one replica on each server.

  Note that Directory replication does not provide fault tolerance for the file system. Only information about Directory objects is replicated. To provide fault tolerance for your files, you must use the host system's fault tolerance system.

• Faster Access Across a WAN Link. If users currently use a WAN link to access some Directory information, you can decrease access time and WAN traffic by placing a replica containing the needed information on a server that users can access locally.

  However, in some cases, WAN traffic could increase due to the NDS synchronization process.

  Distributing replicas among servers on the network allows quick and reliable access because information is retrieved from the nearest available server containing the specified information.