Managing the NDS tree

About partitions and replicas

A partition is a part of the total Directory tree and contains at least one container and its associated leaf objects.

When a partition is subordinate to another in the Directory tree, it is referred to as a ``child partition''. The partition above it is referred to as the ``parent partition''.

You can make copies of a partition, called ``replicas'', and store them on different servers in your network. Distributing replicas reduces network traffic by making information accessible locally and enabling users to log in to the network even when a server is down.

Replicas also provide fault tolerance by ensuring that more than one copy of the partition information is available. If the partition becomes corrupted, you can use a replica to re-create it.

NOTE: Partitions contain only NDS database information, not file and directory data or information.

There are four types of replicas, which are explained in the following list:

Master

Partition information can be read from and written to this replica. The master replica can also be used to change the logical structure of the Directory tree (by creating a new partition, for example).

When you create a new partition, a master replica is created and stored on the same server as the parent partition.

Read/Write

Partition information can be read from and written to this replica. For example, it can be used to log in, add or delete objects, and view directory information.

Read-Only

Partition information can be read from this replica, but it cannot be written to by anything other than a read/write or master replica.

Users cannot authenticate to the network through a read-only replica because the login process changes the NDS database.

You cannot set a bindery context when you log in to a read-only replica.

Subordinate

This replica cannot be modified by any user. It is automatically placed on a server by NDS if the parent partition has a master, a read/write, or a read-only replica on the server and the child partition does not.

If you add a read/write or read-only replica of the child partition to the server, the subordinate replica is removed.