Promoting or Demoting Replicas

Promoting or demoting a replica changes its role in the replication topology. Dedicated consumers can be promoted to hubs, and hubs can be promoted to masters. Masters can be demoted to hubs, and hubs can also be demoted to dedicated consumers. However, masters cannot be demoted directly to consumers, just as consumers cannot be promoted directly to masters.

The allowed promotions and demotions within the multimaster replication mechanism make the topology very flexible. A site that was formerly served by a consumer replica might grow and require a hub with several replicas to handle the load. If the load includes many modifications to the replica contents, the hub can become a master to allow faster local changes that can then be replicated to other masters at other sites.

When promoting or demoting replicas, be aware of the following:

• If you promote a consumer, it becomes a hub. If you promote a hub, it becomes a master. You cannot promote a server directly from consumer to master. You must first promote the consumer to a hub, then promote the hub to a master. Likewise, when demoting a master to a consumer, you must demote the master to a hub before demoting from a hub to a consumer.

• When demoting a master to a hub, the replica will become read-only and be configured for sending referrals to the remaining masters. The new hub will retain all of its consumers, whether hubs or dedicated consumers.

• Demoting a single master to a hub will create a topology without a master replica. Directory Server will allow you to do this under the assumption that you will define a new master. However, it is better to add a new master as a multimaster and allow it to be initialized before demoting the other master.

• Before demoting a hub to a consumer, you must disable or delete all replication agreements to and from the hub. If you do not do this, the demote operation will fail with this error: LDAP_OPERATIONS_ERROR “Unable to demote a hub to a read-only replica if some agreements are enabled”.

  If the hub’s consumers were not updated by other hubs or masters, they will no longer be updated. You should create new agreements on the remaining hubs or masters to update these consumers.

• When promoting a consumer to a hub, its change log is enabled, and you may define new agreements with consumers.

• When promoting a hub to a master, the replica will accept modification requests, and you may define new agreements with other masters, hubs, or dedicated consumers.

To Promote or Demote a Replica

You can use DSCC to perform this task. For information, see Directory Service Control Center Interface and the DSCC online help.

1. Promote or demote a replica by using one of the commands:

   dsconf promote-repl [-d REPL_ID] SUFFIX_DN [SUFFIX_DN...]

   $ dsconf promote-repl -h host -p port [-d REPL_ID] SUFFIX_DN [SUFFIX_DN...]

   $ dsconf demote-repl -h host -p port SUFFIX_DN [SUFFIX_DN...]