Hypervisors overview

This is a brief introduction to hypervisors -- software that allows the implementation of Virtual Machines (VM) in a variety of different hardware, running different operating systems from the one that may exist in the physical machine, like Windows, OS X, Linux, Unix, etc. The hypervisor can also be the basic operating system that will host any other operating systems. IBM created the original hypervisor in 1965 to handle the emulation of prior machines and switch between the then "new" IBM 360 and the emulated machines.

1. Bare-metal or native: it runs directly in the harware is is the host operating system that will allow VMs to be created running guest operating systems. An example of this is type are the VMware vSphere Hypervisor, Xen, and Microsoft Hyper-V hypervisor.

2. Hosted: it runs on top of an existing operating system. The operating system of the machine is called the host, while the operating systems that run in the VMs created by the hypervisor are called guest operating systems. VMware workstation and Oracle VM Virtual Box are the examples of this type that we have seen before and will see in class today running Ubuntu, Windows XP and OS X as guest OSs.

Installing hosted based hypervisors is like installing any program in the guest operating system. Windows, OS X, Linux and UNIX can be used both as host and guest operating systems. In this article you can see an example of Virtual Box running on Windows 7 and hosting a Linux distribution, and this other article you can see VMware Workstation doing the same, just like we saw in class. Virtual Box is free, while VMWare Workstation is not but can be used for a 3 to 30 days free trial period. The machines in the MIS Lab run on VMware Workstations under UB licenses.

The process of creating a VM is similar in most hypervisors and use graphical interfaces to walk you through your choices of guest OS, size of hard-drive, memory to allocate, I/O devices, etc. You may wish to see my tutorial on how to create Ubuntu and Windows 8 VMs using the free VMware Player 5. There is another VMWare tutorial on how to create a VM. Here is a Virtual Box Manual, and You-Tube videos of creating a VM in Linux to host Windows 7, VM for Windows 2008 Server, and Windows 7 in OS X. There is another tutorial on how to Install Virtual BOX in OS X, and then install Windows 8 at this Microsoft page.

A more delicated operation is to create a OS X VM in Windows. You should do this only for test and learning purposes. Apple does not authorize you to install OS X in non Apple machines. You can do this in two ways: acquire a copy of OS X and then install it either in VMware Workstation or Virtual Box -- this is a more "legitimate" way of doing it because you paid for the software. But, if you only want to do see OS X running in Windows as a learning exercise on hypervisors you may use this article to install it in VMware Workstation or Virtual Box.