By that, do you mean banks, payment networks or both? And I guess I'd be curious...

nicholasbraker · 2025-04-25T06:14:45 1745561685

Core transactions and ledgers run on these. Bank I work for now (contracting job) uses them as their core system.

renewedrebecca · 2025-04-24T18:01:22 1745517682

Both. Mainframes though are incredibly good for both I/O and uptime.

Yeah, Linux/Unix are way better on both than they used to be, but on a mainframe, it's just a totally different level.

dralley · 2025-04-24T19:28:41 1745522921

You can run Linux on mainframes fine. RHEL has first-class support for s390x / Z.

leeter · 2025-04-24T19:08:59 1745521739

Not just that. Most operating systems lie about when an IO transaction completes for performance reasons. So if you lose power or the IO device dies you still think it succeeded. A mainframe doesn't do that... it also multiplexes the IO so it happens more than once so if one adapter fails it keeps going. The resiliency is the main use case in many situations. That said IME 99.995% of use cases don't need a mainframe. They just don't need to be that reliable if they can fail gracefully.