Be Our Guest

It's time to talk a little about the guests that have run on VM. I mean what is a host without guests? When I started with VM, it was during the time that the product was more CMS focused, but even then guests were a part of the ecosystem. Earlier blogs mentioned z/VM as a guest, so I won't talk about that too much today.

The first guest I was exposed to was VSE/Systems Package, or simply VSE/SP. Like VM, VSE has a rich history and dates back a few years earlier than VM. VSE/SP was an evolution from DOS/VSE. The product as I knew it was more job or transaction oriented than the interactive CMS. This was real business software. Its use by customers as a guest of VM was very extensive, and there were a lot of programs focused on improving the synergy. I recall a lot of effort on CICS/VM, which was meant to extend the CICS (Customer Information Control System) transaction server into the VM environment as well. Beyond that, there was a lot of work to improve the synergy of VSE and VM. The ability to have VSE and VM handshake on page faults for example. VSE was, and is, an excellent guest.
The VM and VSE interaction was an exciting time. Not only was I exposed to new and interesting technology, but also new people and the Boeblingen Lab. We continue to work with some of those people still on VSE and others on Linux. In particular, I remember Dr. Wolfgang Kraemer, the VSE Performance Leader. I really liked Dr. Kraemer as he was really good at what he did and fun. I still get an involuntary smile whenever I think of him calling me "Billy Boy" with his German accent.

The next guest I would hear about was MVS. It would be described to me as a larger cousin of VSE, offering more function and more scaling. It would later become a component of OS/390, which would evolve into z/OS. Since the introduction of logical partitions to System z, it's become rare for production z/OS workloads to run on VM. However, it is on VM where development of the z/OS system and many of the related software occurs both inside and outside of IBM. The z/OS family has never embraced handshaking technology to the degree VSE did. Part of that is tied to wanting to run the same on VM as it did on bare metal or logical partitions. The height of our involvement with MVS guests may have been in support of Y2K testing. Many customers ramped up their MVS guests, including virtual sysplexes during that time frame. As z/OS Development and z/VM Development often face similar challenges in implementation of new hardware, I've gotten to work with a number of them over the years. Their attention to detail and RAS are impressive.

The 1980s and 1990s also had other guests that I recall. MUSIC (Multi-User System for Interactive Computing aka McGill University System for Interactive Computing) was developed by our friends at McGill University. It was leading edge software that allowed students and professors to create and run their own programs interactively. Another unique guest was MUMPS (Massachusetts General  Hospital Utility Multi-Programming System) . I never ran it myself, but I recall customers who did. Some may classify it as a language environment rather than an operating system, I don't know enough to argue those points. It was used predominantly in the healthcare industry. And then there was also AIX/370, a port of the Unix oriented AIX that today runs on System p.

I must not forget to mention TPF (Transaction Processing Facility) of which the current family is z/TPF. This guest also has a long history going back to the Airlines Control Program (ACP). It's all about fast and efficient transactions. TPF is known for high volume reservation and authorization processing in the travel and finance industries. Like MVS, it is very rare for production TPF workloads to run on z/VM, but there is a lot of testing done on VM. A fascinating aspect of TPF on VM are the vendor additions or extensions to VM, most notably VPARS and VTAPE from VSSI. Which make TPF an even more effective guest.

And then there is Linux. In the late 1990s, I would hear of different discussions of porting it to System z. Then quickly the discussions, turned to rumors, and then reality. Of all the guests, Linux has been the largest game changer. As many of my friends were telling me I should look for another job, that VM was a dead end, there was new life breathed into the VM product. Linux also has the cutest mascot of the guests as well, which doesn't hurt. Linux is more like VSE than some of the other guests. Many of the former VSE team is involved with it in Boeblingen. It's used heavily in production environments. And it has great handshaking with VM.

I joke with a friend that a bed and breakfast might be my next career path. Perhaps the idea intrigues me since I've really enjoyed getting to know the guests staying at Hotel VM.