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sonnyOrullivan

I don't think I need to be reading this. The uptime and several 9s of high availability are attainable with z/OS and a parallel sysplex. No doubt systems like these are used by banks and others in the wild.

But this doesn't say anything about "unbelievably powerful" or "feature-full" as in the OP?

The niche customer claim probably is "will never move off of it because nobody ever wants to touch millions of lines of COBOL" then that's fine. It's likely sane from a business perspective to continue using them as long as maintenance burden is manageable. Luckily managers in those more conservative companies consider full rewrites dangerous, rightly so. But in order to claim otherwise (i.e. unbelievably powerful and thus for everybody) we need to see numbers.

> Consider that partitions are completely isolated from each other. Not some pesky soft isolation either, it's all done in hardware. In practice, every partition in a mainframe is a different logical yet isolated mainframe.

"Completely isolated in hardware" as in isolated by a software hypervisor (PR/SM) that doesn't have a whole lot of hardware support?

> Mainframes are built for different kinds of workloads. They are not cloud machines. They are batch machines with 6 or more nines of uptime.

That's kind of the point. What exactly is the niche, i.e. which new customer with exactly what software and latency requirements would switch from their current system to a z? IBM won't tell you apart from buzzword bingo.

Telum is attached to the L2/L3 so it's that bandwidth as long as the model fits into it. Afterwards you go to memory and you really don't want to compare DDR4 modules with RAIM against HBM3 or the likes that a current compute GPU uses. Latency might be closer but you mentioned bandwidth.
Sorry to say that your previous "evangelism" shows. It would be very interesting to hear what "unbelievably powerful" means (as in facts and numbers) compared to what a hyperscaler can provide. E.g. SPEC for CPU, GFLOPs, Tensor-ops for inference, latency and so on. Last I checked the consolidation story that claimed factors of savings took underutilized ancient Intel boxes as baseline.

"feature-full" is also quite a stretch when it comes to software when most modern software needs to be ported or run in a Linux LPAR.

In addition I'd question that not getting access easily is the main reason for the lack of adoption. It might be part of the problem but the other problem is that the thing is a niche product and IBM doesn't seem to be utterly successful in either explaining what the niche is nor how to extend it.

Re:What type of Machine is the C Preprocessor? on Monday January 27, 2014 @04:35PM (#7133406)
Wouldn't it simply be a linear bounded automaton (LBA)? I understand you can implement recursion via some tricks but only as many steps as you predefine (see e.g. https://stackoverflow.com/questions/7508475/is-c-preprocesso...) This reeks like an LBA to me.