Scalability refers to the ability of an application to predictably handle more load. An application exhibits linear scalability if the maximum amount of load that an application can sustain is directly proportional to the hardware resources that the application is running on. For example, if an application running on 2 servers can handle 2000 requests per second, then linear scalability would imply that 10 servers would handle 10000 requests per second.
Linear scalability is the goal of a scalable architecture, but it is difficult to achieve. The measurement of how well an application scales is called the scaling factor (SF). A scaling factor of 1.0 represents linear scalability, while a scaling factor of 0.0 represents no scalability. Oracle Coherence provides a number of capabilities designed to help applications achieve linear scalability.
When planning for extreme scale, the first thing to understand is that application scalability is limited by any necessary shared resource that does not exhibit linear scalability. The limiting element is referred to as a bottleneck, and in most applications, the bottleneck is the data source, such as a database or an EIS.
Oracle Coherence helps to solve the scalability problem by targeting obvious bottlenecks, and by completely eliminating bottlenecks whenever possible. It accomplishes this through a variety of capabilities, including: