Workload Manager (WLM)
To a lot of z/OS sites, WLM is something that just works, with little oversight or maintenance. Most sites set it up 20 years ago, and haven't really looked at it since.
However, WLM still needs love from time to time, and can provides some features that you didn't expect. So, in this edition, we're taking a closer look at WLM
in our first technical article, we look at WLM Performance Indexes, and how they can be used to quickly monitor the overall performance of a z/OS system. In our second, we list ten WLM issues we often see at z/OS sites: issues that can be quickly fixed.
In our opinion article David Stephens argues that we still need WLM, and still need to regularly maintain and care for it
We hope you enjoy this issue.
technical: How To Show a 10,000 Foot View Of z/OS Performance
Here’s a question. How can you show the performance of a z/OS system? Is the performance good, or not good? If your job is to do exactly that, the chances are that you’re ready to start talking about the different workloads, response time goals for each, and really get into the nitty gritty. Different workloads will have different performance goals: so, your cash IMS transactions may have different performance goals to your customer CICS transactions. And these may change throughout the day: so those IMS transactions could run slower overnight.
To show all this performance, you’ll probably have a lot of graphs, tables and reports. You may have some showing response times for groups of CICS and IMS transactions, and others showing elapsed times for batch jobs or batch streams.
But, there’s an easier way to look at the overall performance of a z/OS system. It comes free with z/OS. And it’s running on your z/OS system right now.
technical: Ten Things I See With WLM Configurations: And Really Don't Like
Whenever I start at a new site, one of the first things I do is to look at WLM to get an idea of how the performance is going. In our partner article, we show how. I've also done a few gigs where clients have asked me to take a closer look at WLM, and recommend changes. In some cases, the WLM setup is good. However, more commonly the WLM configuration could do with some work.
So, let me talk about ten things I often see when looking at WLM that I really don't like, and why.
opinion: Do We Need to Care About WLM?
At a recent site, I took a quick look at their z/OS workload manager (WLM) setup. And it wasn't great. In particular, many workloads had consistent performance indexes (PIs) far higher than 1: these workloads were not meeting their performance goals.
Talking to the z/OS administrators, they said that WLM was last looked at "many years ago" by someone who had since left. Since then, no one had needed to look at it: everything seemed fine.
This is quite common. I regularly see sites with WLM configurations that aren't great. For example, their performance goals may be out, or workloads may be in the wrong service classes. Check out our partner article for a list of WLM issues we regularly see at sites.
But this site highlights an interesting point. Sure, their WLM configuration wasn't perfect. But their z/OS systems seemed to work fine: z/OS administrators weren't aware of any major performance issues. So, why fix something that isn't broken?