Supplier/Consumer; Change Log - Netscape DIRECTORY SERVER 6.2 - ADMINISTRATOR Administrator's Manual

Supplier/Consumer

A server that holds a replica that is copied to a replica on a different server is called
a supplier for that replica. A server that holds a replica that is copied from a
different server is called a consumer for that replica. Generally, the replica on the
supplier server is a read-write replica, and the one on the consumer server is a
read-only replica. There are exceptions to this statement:
• In the case of cascading replication, the hub supplier holds a read-only replica
that it supplies to consumers. For more information, refer to "Cascading
Replication" on page 294.
• In the case of multi-master replication, the masters are suppliers and
consumers for the same read-write replica. For more information, refer to
"Multi-Master Replication" on page 291.
In Directory Server, replication is always initiated by the supplier server, never by
the consumer. This operation is called supplier-initiated replication. It allows you
to configure a supplier server to push data to one or more consumer servers.
Earlier versions of the Directory Server allowed consumer-initiated replication
where you could configure consumer servers to pull data from a supplier server.

Change Log

Every supplier server maintains a change log. A change log is a record that
describes the modifications that have occurred on a replica. The supplier server
then replays these modifications to the replicas stored on consumer servers, or to
other suppliers in the case of multi-master replication.
When an entry is modified, a change record describing the LDAP operation that
was performed is recorded in the change log.
In Directory Server, the format of the change log has changed. It is now only
intended for internal use by the server. If you have applications that need to read
the change log, you need to use the Retro Change Log Plug-in for backward
compatibility. For more information, refer to "Using the Retro Change Log
Plug-In" on page 337.
Replication Overview
Chapter 8 Managing Replication 287