30 

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 JANUARY 2018 

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 OPEN SOURCE FOR YOU 

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 www.OpenSourceForU.com

Admin

How To

S

erver virtualisation (henceforth referred to as 

virtualisation) allows us to run multiple instances of 

operating systems (OS) simultaneously on a single 

server. These OSs can be of the same or of different types. 

For instance, you can run Windows as well as Linux OS on 

the same server simultaneously. Virtualisation adds a software 

layer on top of the hardware, which allows users to share 

physical hardware (memory, CPU, network, storage and so 

on) with multiple OSs. This virtualisation layer is called the 

virtual machine manager (VMM) or a hypervisor. There are 

two types of hypervisors.

Bare metal hypervisors: These are also known as 

Type-1 hypervisors and are directly installed on hardware. 

This enables the sharing of hardware resources with a guest 

OS (henceforth referred to as ‘guest’) running on top of 

them. Each guest runs in an isolated environment without 

interfering with other guests. ESXi, Xen, Hyper-V and KVM 

are examples of bare metal hypervisors.

Hosted hypervisors: These are also known as Type-2 

hypervisors. They cannot be installed directly on hardware. 

They run as applications and hence require an OS to run 

them. Similar to bare metal hypervisors, they are able 

to share physical resources among multiple guests and 

the physical host on which they are running. VMware 

Workstation and Oracle VM VirtualBox (hereafter referred 

to as VirtualBox) are examples of hosted hypervisors.

An introduction to VirtualBox

VirtualBox is cross-platform virtualisation software. It is 

available on a wide range of platforms like Windows, Linux, 

Solaris, and so on. It extends the functionality of the existing 

OS and allows us to run multiple guests simultaneously along 

with the host’s other applications.

VirtualBox terminology 

To get a better understanding of VirtualBox, let’s get familiar 

with its terminology.

1)  Host OS: This is a physical or virtual machine on which 

VirtualBox is installed.

2) Virtual machine: This is the virtual environment created to 

run the guest OS. All its resources, like the CPU, memory, 

storage, network devices, etc, are virtual.

3) Guest OS: This is the OS running inside VirtualBox. 

VirtualBox supports a wide range of guests like Windows, 

Solaris, Linux, Apple, and so on.

4) Guest additions: These are additional software bundles 

Virtualisation is the process of creating software based (or virtual) representation 

of a resource rather than a physical one. Virtualisation is applicable at the compute, 

storage or network levels. In this article we will discuss compute level virtualisation, 

which is commonly referred to as server virtualisation.

A Hands-on Guide on

Virtualisation 

with

 VirtualBox