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What is Virtualisation?

Virtualisation is the creation of a virtual (rather than actual) version of something, such as an operating system, a server, a storage device or network resources.

Virtualisation allows multiple operating system instances to run concurrently on a single computer and by inserting (or installing) a virtualisation layer (or a Hypervisor) on the computer hardware you can effectively separate the hardware from each individual single operating system as per the below diagram.

A Virtual Data Centre (using virtualisation) is a data centre which is created ‘virtually’, effectively in memory, on an existing shared computing platform which would be housed, or located within a ‘Physical Data Centre’.

The Virtual data centre provider will have several very high performance and high capacity ‘physical servers’ and in a ‘virtual’ fashion, segregate and divide the total resources of the physical platform to serve many Virtual Data Centres or Virtual Servers.

This below diagram is a simplified representation of what the layers of the Virtual Data Centre are;
Virtual Data Centre

Physical Layer – is the physical server, networking equipment and routers and hard disk storage devices

Hypervisor Layer – is effectively the operating system which controls the physical hardware and is the ‘container’ which allows multiple ‘virtual machines’ or ‘virtual servers’ to operate on top of a single physical server. The Hypervisor controls the sharing of all physical resources such as memory and processing and ensures all of the ‘guest hosts’ (hosted virtual machines) co-exist and ‘play nicely together’ on the same physical hardware.

Virtual Machine Layer – is what we currently know as the operating system and applications that make up either a server or computer. A good example of a server virtual Machine (VM) would be a Windows Server running Exchange which combined acts as an email and collaboration server, or, the VM could run Windows 7 with Microsoft Office and this could be a user’s desktop machine.

End Users – the end users of the VM could be you or me when we check our email, or type a letter or watch a YouTube video or do whatever else it is that we do as IT consumers. The end user function could also be that of a simple off site backup for all of our important data.

As a simple example, let’s say you buy a physical server from IBM and ensure it is configured with as much memory and processing power as you can get in it. Let’s say you have 100 Gigabytes of memory. Onto that server you could very easily load 10 x Exchange email servers as described above while simultaneously running over 60 x Windows 7 desktop machines for end users.