Partition Replicas

When you create a partition, you create a master replica of that segment of the Directory tree and database. You can create an unlimited number of additional replicas of the partitions on your network and store them on any NetWare 4 servers on the network.

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.




	CAUTION: 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.

Types

There are three types of replicas.

Master replica. A writable replica that contains all object information for the partition. All partition operations (create, join, delete, and repair) occur from the master replica of a given partition.
Only one master replica can be defined for each partition.
Read/write replica. Contains the same object information as the master replica. Allows modifications (writes) to a partition, which are passed to other replicas of the partition.
There can be any number of read/write replicas.

Read-only replica. Contains the same object information as the master replica, but the information can only be read. Used where reading of the partition is required but writes to the partition should not occur.




	NOTE: Log in requires a writable replica. Also, bindery services requires a writable replica. When bindery services is set, use either a master or read/write replica. See chapter 4, "Understanding Bindery Services" for more information.

Partition Replicas

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Purpose

Types