Virtualisation is a development first introduced in the 1970s in which a single mainframe computer could run many separate instances of the same operating system at the same time under the control of a “hypervisor”; in effect each instance of the operating system simulated a stand-alone machine.
All were hosted simultaneously, but separately, on the same hardware.
The use of such virtualisation techniques with Linux style open systems has generated major benefits with single machines supporting multiple virtual servers.
For applications that have relatively low load factors the advantages are substantial, lower capital costs through better utilisation, plus ease of management and provisioning.
The final step to create cloud based computing was the development of the technique known as “orchestration”.
This allows many virtual machines to be managed across a range of physical hardware.
As load increases for a particular application, further virtual machines can be started automatically and, if necessary further physical systems assigned to support of these in-demand virtual machines and applications.
Almost all of the successful web businesses launched in the last 10 years have drawn on this base of virtualised open systems: familiar names such as Google, Amazon, YouTube, Facebook and Twitter all operate in this way.
The combination of virtualised open systems plus sophisticated orchestration leads to the concept of purchasing computing capability as a utility – so-called cloud based computing.
For more on open source systems and cloud computing – download our landmark Open for business report.