Monitoring System Capacity

Monitoring system capacity is done as part of an ongoing capacity planning program. Capacity planning uses long-term resource monitoring to determine rates of change in the utilization of system resources. Once these rates of change are known, it becomes possible to conduct more accurate long-term planning regarding the procurement of additional resources.

Monitoring done for capacity planning purposes is different from performance monitoring in two ways:

• The monitoring is done on a more-or-less continuous basis

• The monitoring is usually not as detailed

The reason for these differences stems from the goals of a capacity planning program. Capacity planning requires a "big picture" view; short-term or anomalous resource usage is of little concern. Instead, data collected over a period of time makes it possible to start to categorize resource utilization in terms of the impact of changes in workload on resource availability. In more narrowly-defined environments (where only one application is run, for example) it is possible to model the application's impact on system resources, leading to the ability to determine, for example, the impact of five more customer service representatives running the customer service application during the busiest time of the day.

Next, we will look at tools that make it possible to observe system resource utilization.