2. PERFORMANCE REPORTING ANALYSIS › 2.1 ILM Analysis › 2.1.2 Usage Guidelines

2.1.2 Usage Guidelines

ILM allows PR/SM partitions to be configured with a defined
capacity, expressed in MSUs. IBM's Workload Manager monitors
the actual LP MSU utilization using a rolling four-hour
average.  If the MSU four-hour average consumption exceeds
the defined capacity, WLM instructs PR/SM to "soft cap" the
LP, restricting processor consumption until the four-hour
average drops below the defined capacity. Thus, with ILM, an
LP can deal with short-term spikes in processor utilization
far above the defined capacity, as long as the four-hour
rolling average remains below the defined capacity.

Group Capacity, a new function introduced with z/OS Version 1
Release 8, allows customers to apply the service units
defined capacity limit to not only a single logical partition
(LP) but also to a group of LPs running on the same server.

This section discusses the application of the concepts
discussed in Section 2.1.4, ILM Concepts. The following
queries will be covered in more depth:

  1 - MSU Consumption Rate and Soft Capping Analysis
  2 - Estimating MSU Consumption of non-z/OS Workloads