What are the advantages of zLinux/Linux s390 on Hercules? [closed]

Question

I set up Debian Linux s390 port to run on Hercules on an i386 computer.

I know that I can now develop apps or run apps that are ported to zLinux/s390 Linux, and perhaps also learn more about the special features of the s390/zseries processors (or at least most of their features). I've also read that there is no reliability/availability/serviceability advantage to running this in emulation since the underlying hardware is not-fault tolerant. Is that even true, given the redundant/fault-tolerant computations performed by the emulated processors?

Does anyone know of other good reasons to run zLinux in emulation?

I am asking because I want to get the most out of the system I set up.

Answer 1

Running Linux for System z on Hercules is good for learning basic principles of how Linux on System z operates. For example, it's possible to learn how mainframe channel devices work (from a Linux kernel hacking perspective, at least).

However, all of the good stuff about System z (redundant I/O, redundant CPUs, z/VM as a hypervisor, etc) aren't present or available with Hercules. What you've read is true, Hercules doesn't emulate any System z RAS capabilities so your reliability would be no better than that of the hardware and OS Hercules is hosted on. It's not as bad as it sounds -- on real mainframe hardware most of those RAS features are designed to be invisible to the operating system anyway, so there is nothing for Hercules to "present" to a guest OS.

It's great for folks who want to verify software runs on S/390 or zArchitecture (s390 and s390x arches) and who don't have access to real mainframe hardware. It's also very useful as an education platform -- I have used Hercules to hack on the Gentoo s390x port.

Depending on the level of mainframe knowledge you have, running Hercules can be a great way to ge a start in Linux on System z. Best of luck!