Oracle Forms N+1 Redundancy

Configuring High Availability for Oracle Portal, Forms, Reports, and Discoverer 14-21 Figure 14–4 Oracle Forms High Availability Deployment 14.4.2.1 Oracle Forms N+1 Redundancy N+1 refers to an approach to redundant capacity that is based on the idea that hardware tends to break in units rather than in groups, meaning that a network of computers is more likely to lose one of its components rather than lose several at the same time. The principal of N+1 is to have as many machines as needed to service the entire user base at peak load plus one additional unit of equal capacity as the machine with the largest capacity in the set. This is often referred to as active-passive failover, since the failover happens on the machine level. If you had six servers in your deployment that can handle the entire user base and are identically configured, they all have an HTTP Server and a Java Runtime and the Forms Runtime installed. There is a hardware or software load balancer to ensure that no single server is over utilized. The load balancer is aware of one machine labeled Standby, which has the same capacity as the machine with the largest capacity among the rest of the set, and is identically configured to all of them, but does not route to it. In an active-passive scenario, the standby machine doesnt have to be running. In an active-active scenario it could be an active part of the set, and provide spare capacity in an ongoing basis. Now lets assume one of the machines fails: If one of the machines fails, the standby machine is brought online and the load balancer has been reconfigured to route new requests to that machine as well, and to ignore the failed machine some hardware load balancers do these two steps automatically. If the standby machine was already running and serving the user base in an active-active deployment, the downtime may be as small as the time it takes to restart the browser on the client. If the Standby machine was not running in an 14-22 Oracle Fusion Middleware High Availability Guide active-passive deployment, and was required to be started, and the load balancer had to be reconfigured manually, the downtime would be longer. 14.4.2.2 Oracle Forms N+M Redundancy