Virtualization has been heavily pushed in the IT industry for about 3 years now, but in some areas the take up as been fairly slow. While in others, the move to Virtualized servers was taken rapidly, maybe even before the technology had matured enough. The Virtualization products from VMWare and now Citrix have come along way in a fairly short time. The Virtual Infrastructure suite from VMWare is still the outright leader when it comes to Virtualization, but Microsoft, Citrix and some other players are starting to weaken the VMWare hold.

That said, should you Virtualize? Presales technicians and sales managers always put a good spin on the tangible and intangible savings you will achieve, but in practice you usually need to expand the number of host servers to meet your actual needs.

The three biggest things you should consider before moving fully into a Virtual server environment are:

1. Cost
2. Capacity
3. Benefits

1. Cost of Virtualizing

Most virtualization proposals list substantial savings that you will achieve by moving to a Virtual Environment. With the green push on everything today, they also quote carbon emission savings and benefits as well. The biggest area where vendors claim savings is the Cost of Ownership. These details will really depend on your particular circumstances. If you virtualize 5 physical servers onto one Virtual server Host that might seem like a good saving, but you’ve spent $5000 USD or so on the license, you will probably need a new server to handle the load. What happens if the new Virtual Server host has a problem? So maybe you need two Virtual Server Hosts and two licenses.

This is where things start getting tricky, and it depends on what and why you are virtualizing. You may also need a SAN, either a full fibre channel model or iSCSI. So, very quickly your costs are now at about $15000 USD and that’s without a SAN.

Now if you find that you need more Virtual Servers running in your virtual environment then you also need more Operating system licenses.

If you want to implement a Virtual Desktop Environment that gets even worse, especially if you want to use Vista. Microsoft has done a good job licensing this. You will need Vista Enterprise with Software assurance and VECD with software assurance for every workstation.

2. How much capacity do you need?

When we looked at Virtualizing we were told we could halve our number of physical servers and still meet the workload needs. Unfortunately it was apparent to me that the pre sales technician hadn’t really taken the time to understand our requirements. The metrics taken before the proposal are taken on a time interval basis and can not capture the true CPU and memory usage. 

I have heard of people successfully virtualizing Citrix servers, but in my study I found very poor capacity and performance on a single vCPU Citrix server and marginally better capacity on a vCPU server. So this is where two things come into play. The first is the hardware you are using? The better the hardware the better the performance. The server I was using was a new 2 x dual-core server with plenty of ram. 

The second thing to consider is how your users use the servers? Old and poorly written applications can have a dramatic affect on server performance. If you have 10 physical Citrix servers for instance, you might need 15 or 20 virtual Citrix servers. 

3. Are you really going to get any benefit?

For all the savings you are suppose to make and the benefits of centralised management, are you going to be in a better position to meet the corporate IT needs. If you work in a static environment is it really important to have a flexible infrastructure. Why do you want to Virtualize, make sure that you have some real goals for Virtualization before you get the Vendor in. I think organizations make decisions based on flawed or inaccurate beliefs about the quality of service you will gain. Just remember a virtual server performs worse than a physical server. Someone said to me once that “virtualization is good for consolidating servers that aren’t very busy, but a Citrix server is not one of them”, I think this is very true.

Can Virtualization help?

You might think that I am anti-virtualization, but I am not. I think virtualization is a good technology concept and can really help organizations. For instance it has made testing and development work really easy, you no longer need old servers to run test applications on. 

I use it all the time and will continue to use it. Up until a few weeks ago I didn’t think you should virtualize Microsoft Exchange, but I see it has now been done in a fairly large organisation. Should you virtualize SQL servers and file servers? 

I think the biggest thing you need to do is consider these three points. Virtualization technology is getting better every day, servers have more processing power, solid state hard drives are coming and competition is getting stronger between the three or four main vendors. 

Licensing Microsoft Operating systems and applications will always be an issue.

Give virtualization a try, if it works for you, then great. Don’t virtualize because you read somewhere that you should.