A quick introduction to server virtualisation

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This might seem an odd post to write, given that server virtualisation has been around for years, however at a couple of recent events I was at it became obvious that there still loads of intelligent, reasonable IT professionals who don’t understand what it is.  If that’s you please read on if not I won’t be offended if you click away now.

So what is server virtualisation and why should you care?

It started off as a simple recognition that most servers and PCs are largely idle , running at between 10-15% of capacity.  This is waste the capital asset – the hardware itself and it also consumes a lot of unnecessary power. 

The concept is a simple one: run multiple virtual machines (VMs) on one physical server, each with its own operating system and applications. Each disk in a given VM shows up as a single  file on the physical server and other resources such as networking memory and cpus are then assigned to each VM through some sort of console (depending on the vendor). 

So implementing this approach means that one server is now doing the work of 6 –10 servers, and this gives all the benefits of less power less cooling and less space in needed in a data centre.  There is also now the possibility to move VMs from server to server to balance workloads, to copy them for testing e.g. applying patches etc.  and development.

Desktop operating systems like Windows 7 can also be run as VMs on servers and end users can then connect to one of these from a thin client device or any old desktop to create a Virtual Desktop Infrastructure (VDI)

Of course there are downsides to server virtualisation:

  • The failure of any of few physical servers left will have a bigger business impact so steps should be taken to make them highly available.
  • Each VM still needs to be maintained patched etc.
  • VM sprawl can be an issue now that it is so easy create new VMs to management and control are essential.
  • It’s not obvious which VMs are mission critical and who owns them so management and control critical.

However these have not prevented many organisations adopting this on a wholesale basis for their production environments and there is a healthy job market for  IT Professionals who are experts in that field. Many of the skills required are simply an extension of what most of us do today in configuring physical servers, however the setting are now done in management tools or via scripts rather than, fiddling with actual hardware.

To find out more about virtualisation Microsoft has the Microsoft Virtual Academy , a collection of online resources to help  people new to virtualisation get up to speed complete with simple tests to make sure it’s all sinking in.