Introduction to Virtualisation

Definition : A Virtual Machine

A virtual machine was originally defined as "an efficient, isolated duplicate of a real machine". Current use includes virtual machines which have no direct correspondence to any real hardware.

So for example, if you have a PC or Server that has Windows and an application installed such as a SCADA system, that performs a critical function, then we can turn this into a ‘Virtual Machine’.

Definition : An ESX Host

We then introduce a physical piece of hardware known as a Host. This is essentially a PC, however its installed operating system (ESX) is then able to support multiple Virtual Machines all running together at the same time.

Therefore it is entirely possibly to make many Virtual Machines (one for each of your existing physical PC’s) and then run them all on one ESX Host !

Each Virtual Machine (VM) still behaves like a normal PC, with a unique IP Address and PC Name, and you can reboot it and install software just like the real thing !

So immediately you have reduced the number of physical PC’s and are already saving energy !