Peeling the Virtualization Onion without Tears

The virtualization wars will heat up in 2008 as competitors vie to provide the management hub for virtualized utility infrastructures in the enterprise. Microsoft, for example, has announced its intention to become a dominant player for what they call “Dynamic IT.”

However, virtualization is not one technology but several. It's time to take a step back and review what virtualization is and how it works. This note reviews four main types of virtualization:

1. Hypervisored or Virtual Machine Virtualization.
2. Operating System Virtualization.
3. Application Virtualization.
4. Presentation Virtualization.

Virtualization is essentially a trick that fools software or hardware into thinking it is dealing with something real, when in fact it is interacting with an abstraction. The various forms of virtualization are differentiated by where that “abstraction layer” occurs.