Server Virtualisation

This section refers to Industry Standard (or X86) Servers. Virtualisation technology has been available in Unix and Mainframe servers for many many years however, the vast majority of servers deployed are Industry Standard and it is the virtualisation of these servers which has really caught user's interest in the last few years.

A server is a system which can be broken down into three logical elements - Hardware, Operating System and Software Applications. A virtualising layer of software called a "hypervisor" can be installed which de-couples the Operating System and Applications from the Hardware. Hypervisors have been developed by a number of vendors including VMware, Microsoft and Citrix – among others.

The combination of operating system and applications in this scenario is referred to as a “virtual machine” or VM (sometimes also called a "guest" machine or system). This is because it represents, for all intents and purposes, the identity and function of the server. The hardware simply provides computing resources to this virtual machine such as processing power, storage, memory and network access. The physical server which supports VM's is referred to as the "host" machine or system.

Note that the server system will behave exactly the same as before the hypervisor was added. We have changed the architecture of the system internally, but not actually achieved any real benefits yet. The biggest single reason that server virtualisation is set to dominate future data-centres, is that non virtualised servers are typically running at well under 10% utilisation. In other words, the resources provided by today’s hardware are massively bigger than a single server typically needs.

With server virtualisation – we can now replace physical machines with virtual machines. The more powerful your host server, the more virtual machines can be hosted. Ten or more virtual machines on a single server is not uncommon. The cost savings possible by using this approach are enormous - both in terms of hardware costs and running costs (power, cooling and manpower to manage the servers).

If organisations have server systems which are nearing end of life – virtualisation may be a far better option than simply replacing them physically. It is estimated that the number of virtual server sales worldwide exceeded physical server sales during 2009. The server world is going virtual.

Server virtualisation is being considered by many organisations across all industry sectors. Systems have traditionally been deployed with at least one server per application. Now, a single host server can run a multitude of applications. The advantages do not stop here - watch this video tutorial to get a fuller picture. (Note that although this video is aimed at those selling IT - the description of virtualisation is equally useful for buyers of IT).

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