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In many discussions about using the cloud for computing or hosting, the term 'virtualisation' often crops up. Many observers will refer to virtualisation and cloud computing or cloud hosting as if they are interchangeable. This is, however, not the case. Virtualisation and the cloud are very different things although in many cases they can be used together to improve efficiency and cost. Both virtualisation and the cloud are technologies that will be increasingly utilised in the near future of computing. Though virtualisation can be used in a number of ways, one of the most common is server virtualisation.

So what is server virtualisation? This specific kind of virtualisation is where a physical server is divided into multiple 'virtual environments'. These virtual environments are isolated and run independently from one another. Virtual environments can also be known as 'virtual private servers', 'guests' or 'emulations', amongst other things. Whatever they are known as, these virtual environments can run different applications and carry out different tasks because they are effectively separate servers within one physical server. Previously administrators would often dedicate one physical server for each application or task - resulting in a large number of physical servers. With virtualisation the tasks can be delegated to a virtual dedicated server within a physical server.

There are a number of advantages to virtualisation. As it is no longer necessary to have a physical dedicated server for each task or application the total number of servers required can be reduced. A reduction in physical servers can mean a reduction in costs (as you no longer have to maintain and manage such a large number of servers) but also a reduction in energy costs. Running servers will use up energy as they need both power and to be kept in specific temperatures, having less servers will mean less energy being used - virtualisation can often be seen as a 'greener' alternative.

In addition, virtual environments can run completely different operating systems and can also provide developers and programmers with completely separate server space to test or develop applications. If you use virtualisation, you can make the most of your server's resources. Even though many applications often need to be on separate dedicated servers, most applications will only use a small proportion of the server's abilities. Dividing up your server into several virtual environments can help you to maximise your server resources whilst keeping applications separate. You will have to be aware that dividing up your server through virtualisation will also effectively divide up the server's processing power - so you should not build too many virtual environments on one server. When the server does not have enough processing power, all the applications will slow down and the server could even crash.

So how does virtualisation differ from using the cloud for computing or hosting? Cloud hosting and cloud computing utilise a group of servers (known as a 'cloud') - the resources for cloud computing or the space for cloud hosting are spread across a number of servers which improves uptime and performance. In very basic terms, virtualisation allows one server to perform the work of many while the cloud utilises a number of cloud servers to provide applications and computing resources to a user across the internet. Though they are very different processes, virtualisation and the cloud can be used together. Cloud computing can be carried out without the need for virtualisation but it can be particularly advantageous to use them together to improve efficiency and save space and money.

Data centres, especially those that provide cloud services, can benefit from virtualisation. A data centre is effectively a centralised space for the management, use and storage of data and information and can be either 'physical' or 'virtual'. A virtual data centre is where all the cloud resources available are combined (e.g. hosting, computing etc.) and made available over the internet. Within a virtual data centre, you can create and maintain your own virtual servers. A virtual data centre might be an appropriate choice for companies that want to run video conferencing systems, video campaigns or online applications. Virtualisation is an important tool that is scalable (from creating two virtual environments in one physical server to creating a virtual data centre) and can help companies to save money and make the most of their server resources.

© Izzy Evans 2012

If you would like to find out more about cloud servers and virtual data centres then you can visit What Are Cloud Servers?.