Use One Big Server (2022)

This isn't even the end game for "one big server". AMD will give the most bang per rack, but there are other factors.

An IBM z17 is effectively one big server too, but provides levels of reliability that are simply not available in most IT environments. It won't outperform the AMD rack, but it will definitely keep up for most practical workloads.

If you sit down and really think honestly about the cost of engineering your systems to an equivalent level of reliability, you may find the cost of the IBM stack to be competitive in a surprising number of cases.

At what cost politically? I would expect political battles to be far more intense than any of the technical ones.

That’s because 75% (citation: wild-ass estimate) of tech workers are incapable of critical thinking, and blindly parrot whatever they’ve heard / read. The number of times I’ve seen something on HN, thought “that doesn’t sound right,” and then spent a day disproving it locally is too damn high. Of course, by then no one gives a shit, and they’ve all moved on patting each other on the back about how New Shiny is better.

no. In the short time I work at a z/OS-shop, they had to IPL twice. And the IPL takes ages...

Now, if you can live with the weird environment and your people know how to programm what is essentially a distributed system described in terms noone else uses: I guess it's still ok, given the competition is all executing IBMs playbook too.

Entire mainframe IPL, or just LPAR?

My understanding is that usually you subdivide into few LPARs and then reboot the production ones on schedule to prevent drift and ensure that yes, unplanned IPLs will work

I do wish this field were more scientific and factual. Rather, it more closely resembles cults.

I agree. I always cringe when I see a job posting where they're wanting to hire a "passionate" xxx engineer. I always think to myself, "no, you really don't. you want to hire a dispassionate engineer who is objective". It's very difficult to be objective when you're passionate about something (especially a technology). And then what do you do with that passionate person when the organization gets rid of the technology that they're passionate about?

ETA - fixed spelling error