What is a Virtual Server?

Traditionally, servers with Intel processors have been dedicated to run one single operating system per physical machine. This being determined by the particular operating system loaded on the primary disk drive.

Typical examples are Microsoft Windows Small Business Server, Microsoft Windows 2003 and now a growing trend towards also using Linux.

With virtualised systems, the user can create and run many separate "virtual machine" instances and these can either be all the same operating system or all totally different. So for example, a single virtual server may run several Linux installations, a Windows 2003 installation and a Windows Xp installation all at the same time.

This process is achievable because KVM modifies the core Linux operating kernel, which then becomes a "hypervisor",  designed specifically to optimise the system resource allocation amongst the multiple virtual machines.

Many servers actually spend a large proportion of their time idle and not performing useful work and it is this fact that the virtualisation process takes advantage of.