Oracle RAC Isn't Just for Databases

Depending upon how your day is going, you might think of Oracle Real Application Clusters (RAC) as being as sweet as a Tootsie Pop or as a technology that leaves you in tears like a freshly peeled onion. Regardless of your view, what you'll find at the center of Oracle's RAC database technology is Oracle's very own clustering software. However, you might be surprised to learn that this technology can be used, with Oracle's blessing no less, as general purpose clusterware -- cluster software to provide failover capabilities for your third-party applications. You don't even need to be running their database. In this article, I will review Oracle's clusterware technology at a high level and present a simple configuration for demonstration purposes.

There are different cluster technologies for delivering different types of clusters. Oracle's RAC database technology is known for providing scalability through its active-active database cluster technology. While some clusters help scale throughput by providing parallelism, Oracle's clusterware provides a failover technology. How Oracle databases scale using this technology in an active-active manner is a topic for a different article, but what is important here is that this same technology can support an application in an active-passive manner.

Not surprisingly, the hardware requirements are not all that different from other popular cluster technologies. You will need the software, which you can freely download from Oracle Technology Network (OTN). You will need to license at least one of the nodes in the cluster for Oracle database standard edition or better. This is the technology used by RAC, and although there must be some real limit to the number of nodes that you can have in a cluster, there are RAC clusters out there that are 64+ nodes.