[shub]

Reminds me of an IBM technical bulletin I found, somehow, about 10 years ago. It advised that if you were moving from this z9 hardware configuration to that one, you would have 30 minutes of downtime. Implying that other changes required no downtime, which I inferred wasn't stated because it wasn't insanely awesome to mainframe guys, adding CPUs and RAM to a running system was just how things worked.

I was in college at the time and looked at job postings for mainframe programmers because I wanted to work on that. Never found one that required less than 5-10 years experience, not then and not when I've checked every couple years after that. Too bad; I quite liked the idea of working in an ecosystem that starts from "let's make this work every single time" instead of "let's make this work well enough to keep customer complaints to a dull roar".