Replication Agreement - Red Hat DIRECTORY SERVER 8.1 - DEPLOYMENT Deployment Manual

Consumers
A consumer server must:
• Respond to read requests.
• Refer update requests to a supplier server for the replica.
Whenever a consumer server receives a request to add, delete, or change an entry, the request is
referred to a supplier for the replica. The supplier server performs the request, then replicates the
change.
Hub Suppliers
In the special case of cascading replication, the hub supplier must:
• Respond to read requests.
• Refer update requests to a supplier server for the replica.
• Initiate replication to consumer servers.
For more information on cascading replication, see
6.1.1.4. Replication and Changelogs
Every supplier server maintains a changelog. A changelog is a record of the modifications that have
occurred on a replica. The supplier server then replays these modifications on the replicas stored on
consumer servers, or on 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 changelog.
The changelog size is maintained with two attributes, nsslapd-changelogmaxage or nsslapd-
changelogmaxentries. These attributes trim the old changelogs to keep the changelog size
reasonable.

6.1.1.5. Replication Agreement

Directory Servers use replication agreements to define replication. A replication agreement describes
replication between a single supplier and a single consumer. The agreement is configured on the
supplier server. It identifies:
• The database to replicate.
• The consumer server to which the data is pushed.
• The times that replication can occur.
• The DN that the supplier server must use to bind (called the supplier bind DN).
• How the connection is secured (TLS/SSL, Start TLS, client authentication, SASL, or simple
authentication).
• Any attributes that will not be replicated (see
Fractional Replication").
Section 6.2.3, "Cascading
Section 6.3.2, "Replicated Selected Attributes with
Replication Concepts
Replication".
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