The Cold Failover Cluster Configuration in Conjunction with Oracle Internet Directory Replication

To provide additional availability and scalability, you can use the cold failover technique in conjunction with Oracle Internet Directory Replication. Figure 28-3 illustrates this configuration.

Figure 28-3 Directory Replication in Conjunction with Cold Failover Configuration

Text description of the illustration oidag108.gif

As Figure 28-3 shows, on a two node cluster, Virtual Host VHA is hosted by Physical Host A and Virtual Host VHB is hosted by Physical Host B.

Oracle Internet Directory Node 1 is installed and configured on Virtual host VHA.

Oracle Internet Directory Node 2 is installed and configured on Virtual Host VHB.

Both Oracle Internet Directory nodes are configured for multimaster replication.

LDAP applications can do either of the following:

• Communicate directly with either Oracle Internet Directory node by using the respective virtual host names for the LDAP host

• Load-balance by means of a LAN re-director or another third-party solution that connects to the two hosts on which the Oracle Internet Directory nodes are configured

  See Also: "An Oracle Internet Directory Node"

Using cold failover in this way represents an improvement over the simple cold failover configuration. There are two Oracle Internet Directory nodes and the two are in multimaster replication. Oracle Internet Directory is active on both cluster nodes and hence presents an active-active configuration. In contrast to the cold failover-only configuration, which is an active-passive configuration, the Oracle Internet Directory services are actively available on both cluster nodes at any given point in time.

The Cold Failover Process in Conjunction with Oracle Directory Replication

Figure 28-4 shows the cold failover process in conjunction with Oracle directory replication.

Figure 28-4 The Cold Failover Process in Conjunction with Oracle Directory Replication.

Text description of the illustration oidag109.gif

As Figure 28-4 shows, when Physical Host A fails or is unavailable because of maintenance downtime, the cluster software fails over virtual host VHA to Physical Host B. The Oracle Internet Directory processes that were previously running on Physical Host A are then restarted on Virtual Host VHA, and replication is resumed.

LDAP applications communicating directly with Oracle Internet Directory Node 1 by using host name VHA experience a momentary service outage. After the failover is complete, these applications must reconnect by using the same host name, namely, VHA. The momentary LDAP outage can be avoided completely if the two Oracle Internet Directory nodes are front-ended by a LAN redirector for load balancing.