Introduction

There are three major types of virtualization that are put into use almost every day in computing. Each of these make our lifes both easier and more painful. I will be talking about VMware and Xen because of them being the leaders in enterprise virtualization while also offering a free products to use.

The three main types of virtualization are:

• Full-Virtualization
• Paravirtualization
• Application Virtualization

Full Virtualization

Most of VMware products use the full-virtualization implementation because of its capability to completely isolate itself from the host machine.

IMPORTANT: This is not totally true, there is a great podcast from Paul Dot Com which explains the possibilities of breaking out of a guest virtual machine into the host machine

Paravirtualization

Xen on the other hand implements Paravirtualization which enables for a still secure but optimized interaction between the guest and the hardware. This is because the kernel used in the guest must be ported to implement the API calls to the Xen Kernel.

Application Virtualization

This virtualization occurs at the application layer. A great example of this type of virtualization is the Java Virtual Machine. There is a layer where the java applications interact with and the Java Virtual Machine actually handles the interation with the operating system itself.