Linux® on the Mainframe

14.6. Performance tuning and capacity planning

Performance tuning aims to alleviate imbalances in system resources where one resource is underutilized because of constraints introduced by other resources. This section discusses I/O as one of the resources to be balanced. Although the diagnostics that reveal I/O shortcomings belong to the performance management discipline, I/O is discussed here because any corrective measures are usually the responsibility of the data administrator. For a more general discussion, see Chapter 15, “Performance and Capacity Planning.”

In the mainframe tradition, the CPU is regarded as the most important part of the system, which must be kept busy whenever work is to be done. The mainframe's I/O subsystem has, therefore, ...