Introduction

Virtualization is a fancy word, but what it means is that you can encapsulate entire operating systems or parts thereof in a bubble of virtual hardware and software so that it appears like a complete, separate and real physical host to the software contained inside this bubble. Think Matrix.

Virtualization has two dimensions: interaction between the physical host and the virtual host and the interaction between the virtualized operating system and the underlying hardware.

Virtualization software is normally run as an application or a service on top of an operating system, like Windows, Linux, Mac OSX, etc. In technical terms, the physical machine is referred to as the host. Inside the virtual software, an instance of an operating system is executed, which can be similar or identical to the one powering the host. In technical terms, the virtualized environment is known as the virtual machine and the operating system running inside as the guest.

Furthermore, there are different ways the virtualization is brought to realization. There's simple emulation, where hardware and software calls are passed through a translation layer. There's para-virtualization, where parts of the activity inside virtual machines are passed onto real hardware while others are emulated. There's operating system level virtualization, where you boot into a dedicated kernel that permits only same instances of the operating system to run.

Some of these methods can be performed on the fly, without significant changes to the host and its operating system. Others require that you reboot your host into a dedicated instance of your operating system that supports virtualization. Others yet require a complete machine to be used for virtualization only, also known as bare-metal virtualization.

Virtualization software that manages the creation and running of virtual machines, the allocation of resources and the containment is often known as the hypervisor. Some virtualization products can also use the CPU technology virtualization extensions to boost the performance of virtual machines. This is known as hardware-assisted virtualization and make use of technologies such as VT-x (Intel) and AMD-V (AMD).

Source: www.techsupportalert.com