When there is not sufficient capacity for all work in the system to meet its goals, business importance is used to determine which work should give up resources and which work should receive more. You assign an importance to a service class period, which indicates how important it is that the goal be met relative to other goals. Importance plays a role only when a service class period is not meeting its goal. There are five levels of importance: lowest (5), low, medium, high, and highest (1).
Figure 1 shows an example of the relationship between workloads and service classes. Work in the figure is represented by different size triangles. The IMS™ workload in the figure, represents all of the IMS work. There are three single-period service classes set up, each with a different importance, and a different response time goal.
Figure 2 shows an example of a workload that is organized by division. In the figure, work is represented by different shapes: circles, squares, and triangles. The OFFICE workload represents all of the work in the office division. There are three service classes set up, each for a different kind of work in the OFFICE workload. The IMSTEST class represents the IMS test work, CICS® represents all of the CICS work, and JES represents all of the batch work in the OFFICE workload. Each of the service classes has one period with a different response time goal assigned to it.
