Virtual computing for free

Posted on 12 Oct 2009 at 12:09

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Running multiple virtual operating systems direct from your desktop isn't as tricky as it sounds. Jon Thompson explains all you need to know.

Virtual computing is fast becoming a viable alternative to maintaining several computers in parallel, and it's a useful tool for both businesses and home users. Large companies are beginning to realise that it can reduce their hardware costs and carbon footprints, as well as simplify the process of maintaining several servers with different operating systems. Home users can also take advantage of the increasing number of free virtualisation packages to run multiple operating systems on the same desktop, rather than having to maintain a multiple booting system.

What is virtualisation?

Virtualisation software essentially fools different operating systems into believing that they're the only ones running on your computer's hardware. In reality, each runs on what's called a virtual machine, in which the virtualisation software intercepts calls from each operating system to the BIOS and drivers so that each machine seamlessly shares the available resources.

Virtual computing is ideal for testing out new versions of operating systems, such as Linux, without committing any hardware by overwriting any existing operating systems. It can also help rationalise your current sprawl of computers into one streamlined system. If you're a Mac user and need a piece of software that runs only on Windows or Linux, you can use virtualisation to run it on your desktop.

Virtual computing also has the advantage that you can take snapshots of operating systems. If you install new software that makes a mess of the operating system, or it picks up a virus while online, you can simply close and delete the virtual machine and revert to the saved snapshot. Better still, nothing else - including the host operating system upon which the virtualisation software runs - will be affected.

Using VirtualBox

In this feature, we're going to show you how to use Sun Microsystems' VirtualBox to run several operating systems simultaneously on the same computer. The VirtualBox application is installed on the host computer just like any other software. Once installed, VirtualBox allows you to create a series of virtual machines on to which new operating systems (called guest operating systems or 'guests') can be installed and run at will. In this example, we're using Windows XP, but the procedure for installing and using VirtualBox under Vista is the same.

Though VirtualBox itself requires only about 30MB of hard disk space and is fairly light on RAM, each of the guest operating systems will require a fair amount of disk space - after all, they need to install just as they would on a new PC. You'll therefore need a fairly large hard disk with plenty of free space. The other resource you need lots of is memory. With enough memory (and a fast processor), it's possible to create a whole network of virtual computers on the desktop and run them simultaneously.

While performance issues in standard, non-virtual operating systems can often be solved by adding more RAM, in a virtual computing environment, the speed of the processor has a large bearing on the overall performance of each guest operating system. At the bare minimum, the processor will be running the host and guest operating systems and taking care of all requirements for seamless virtualisation.

Installation

Installing the VirtualBox application isn't a tricky task and you can find the Windows executable on Sun Microsystems' VirtualBox website (www.virtualbox.org). After downloading, simply double-click on the installer executable to run it. Accept the initial licence agreement when it pops up and press Next. The subsequent screen gives you some setup options. Since you'll almost certainly need networking and USB support, leave these two options selected and press Next twice to continue.