Spending Time in the Fort

Growing up we all had moments where we pretended to be a fireman, or policeman, or the Lone Ranger, or Captain Kirk, or a System Programmer with our own z196. They tell me playing is one of the ways we learn. I've found it interesting over the years to watch how different people learn.

I believe VM helps us learn how VM works, as well as System z in general. One of my early assignments was to build my own second-level system. And it's still something I recommend to our new hires no matter which discipline (development, system test, performance).  You learn a lot about how the system is 'put together' in the process. Once you have your second level system, you have a new proving ground or playground.

Most of us in the Development Lab these days are still somewhat focused or specialized. A second level system allows us to explore other aspects. For example, we most often think about a z/VM system that is up and running, and these days they just run and run. So we don't often see initialization or shutdown. Both are important to understand and our second-level systems give us a chance to see and experience that. I've heard that some customers schedule shutdown/IPLs just so there operators get a chance to practice, particularly IPLing the system. Lots of things can be learned or practiced by doing this on second-level system.

Once I had my second-level system, I was able to try almost any command, especially the harmful ones. Seeing is believing. Does cold start really erase all the user spool files? Well, by golly, it does. Good thing I did that second-level. Occasionally, I need to give a customer a procedure to follow. While our documentation is good and I've been around a long time, I still often test it out second level. This way I can match the customer level better, avoid customizations that may be on my production first level, and validate things closer. One time last year when I skipped this, I missed an important aspect of the procedure related to privilege classes.

Beyond this, I found my second-level system gave me a reason to build automation or customization around it. It's interesting to wander around the Lab and see that a lot of people have written their own tooling for their second level systems. Some of it is incredibly elaborate. Using temporary disks or virtual disks in storage for their page space or perhaps also spool space. Various programs to generate loads or start of one-off applications. Just amazing the creativity that occurs in that space.

For those that love VM, their second-level system is a place of fun. At times it makes me think of the fort we built in the neighbors barn. The hours of creativity and fun spent in that fort, and in my second-level system. Spending time in both of them has made me late for dinner more than once.