Hypervisor on LinuxONE - z/VM

I mentioned earlier already, on LinuxONE there exists multiple Hypervisor. But why?

In LinuxOne Virtualisation I gave a high level overview on PR/SM which is the Typ 1 Hypervisor enabling the customer to share and reuse hardware direct without an additional operation system.

To get a better understanding why we have hypervisor it is good to think about what situation had been present at that point in time. Honestly with the current sustainability and power consumptions discussion we are at the same situation as it had been many years ago.

First things first, why Hypervisor at all? I think I can say the main reason is to use the existing hardware in the most optimal way and consolidate on less physical space by enhancing the system to share. With PRSM it was possible to reduce the amount of physical server space, as multiple programs/applications/workload could run on the same hardware in an isolated format. As the capabilities of technology grew and the need to more and different compute resources grew the next level of consolidation came into focus.

In the 1970's IBM officially started to market a technology already used. That was the beginning of Virtual Maschine or short VM. VM or z/VM is not the hypervisor, it is the product and management around the hypervisor. The Control Program (CP) is the hypervisor used in this case. And there I have to admit that the timeline is not 100% correct. I talked to Frederik Hartmann and he reminded me that the CP (or its predecessor) was already available prior to the ability to create logical LPAR. It's capabilities had been used mainly internal to develop new capabilities on existing hardware.

zVM is capable to run all System Z operation systems as well as Linux guests within one environment providing it a wide range of options. It provides a highly configurable runtime environment for IBM System Z customers. You see its heritage within it's out of the box configuration tooling and options. IBM and other vendors did provide alternatives for the day2day operation in case the skill set is not available.

Capability's of zVM are

• Resource Virtualization (CPU, Memory, disks, network)
• fine grain resource sharing for Linux guests
• Environment clustering of up to 4 zVM systems
• and more

More high level details on the hypervisor can be found here or you can listen to the education material on zVM.

The next Hypervisor to talk about will then be KVM.