The MVS Workload Manager (WLM) was first introduced with MVS/ESA 5.1. Since then, it has evolved to become one of the most integral parts of the z/OS operating system and to IBM’s overall strategy for self-managing, self-healing, and self-tuning systems. I remember when WLM was first introduced, many performance analysts were concerned their jobs would be eliminated or that they would lose control over system performance. Well, I can confidently say that neither has happened.
Over the years, I’ve worked with dozens of installations that were either migrating to goal mode or were already in goal mode and needed to fine-tune their WLM Service Definition or goals. I’ve worked with installations whose systems were having problems meeting WLM-defined goals, as well as with installations that were having problems managing their goal mode systems. My WLM classes are filled with students who want to get that sense of confidence in the z/OS WLM by understanding why it treats particular workloads certain ways.
Although no two situations or questions are ever the same, I have come to conclude that most, if not all, the phone calls, assignments, inquiries, and student questions fall into a set of scenarios and situations.
This article presents these scenarios from a high-level approach. If you recognize your installation, your z/systems, or yourself in any of these scenarios, then I recommend you put “Investigate possible changes to WLM Service Definition” on your project to-do list.
This article will not delve into methodologies for conducting goal mode evaluations or discuss how to determine what changes need to be made in a particular situation. Rather, this article will provide insight to WLM and help you structure your WLM responsibilities.
SCENARIO 1: IMPROPERLY SET GOALS OR WLM CONTROLS
Your migration to WLM goal mode was successful and compatibility mode is now a thing of the past. However, some goals have never regularly been met, or some work is not being managed as expected by WLM. Why is this? Could it be due to improperly set goals or incorrect service definition setup? The answer to this question is absolutely yes.
Installations had a variety of methodologies to choose from to help them migrate to goal mode. These included developing a service definition from scratch, using a sample service definition as a guideline, attempting to translate pre-existing IPS/ICS controls into a WLM Service Definition, or some combination of all three. Any methodology, mixed with a slight misunderstanding of WLM, made it possible to set improper goals and/or WLM definitions.
Although I have seen many different cases of improperly set goals and WLM definitions, some of the more common and easily explainable reasons include: