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Desktop Virtualization vs. Physical Desktops: Which Saves More?

One of the biggest hurdles for desktop virtualization adoption is price. Through all my interactions with customers, I am always hearing: "I heard it was more expensive, I heard there are no cost savings," etc. So, let's compare a desktop virtualization rollout versus a traditional physical desktop rollout and see if it truly is more expensive.

That being said, keep in mind that from a CapEx expenditure stand point, you will not see much savings. But you will see significant OpEx savings. Usually when I say this, customers will say, "My CFO does not care about OpEx, we can quantify OpEx, we can't touch it." I say, have a little more faith. I will accept that argument and respond to you as follows: While it is not easy for every organization to quantify or justify OpEx, the next time your manager needs a project completed in a week and you have no cycles or your current employees have no cycle, the only option is to hire more help or use consultants.

The next time your CFO's laptop breaks down and it takes two days (being generous) to replace it and bring him back to productivity, the next time your CFO or CIO flames you for not providing adequate technical support or timely technical support to the user community which is generating money for the business, at that point you can reply to them by saying, "We have no cycles, we have been supporting our dispersed and remote user community for years using dated methods; we need a change." At that point, the OpEx will all of a sudden look very lucrative.

Let's proceed with the following scenario: Gordon Gekko Enterprises has 1,000 physical desktops that are 7 years old running Windows XP and are up against a hardware cycle refresh and an operating system upgrade to Windows 7. Let's also assume the company has done its homework and knows the benefits of desktop virtualization. The company is interested in a ball park price comparison between physical and virtualized desktops. To accomplish this, I am choosing the VDI type of virtualizing desktops. While there are other types that can be used to lower the cost, I'm going to assume worst-case scenario.

The company ran all the proper assessments and identified 15 IOPS per user as an acceptable number. (We'll keep it simple and not go into the different profiles etc...) The company has also identified that it wishes to give each VM running Windows 7 2 GB of memory and 1 vCPU. Again, we are going to ignore application delivery and assume they have that figured out. The company has also identified that they wish to use shared storage in the form of a SAN and have taken the proper steps to avert bootup and login storms as well as anti-virus storms, etc...

Gekko wants to use blade technology to support this environment and its calculations and risk factors accept 60 VMs per host. The math would be as follows:

1000 VMs / 60 VMs per host = 16 hosts

Considering 2GM memory per VM, this would translate into 120GB (128 of course is the right configuration) memory per host. The following tables show the TCO.

Table 1. Desktop Virtualization TCO


Table 2. Physical Desktop Rollout TCO

When reading these numbers, you can of course draw your own conclusions. Still, I want to discuss a few here and invite comment from you.

Now keep in mind I have put a lot of thought into this, so read the numbers carefully. I have also been very generous with these numbers.

For example, you can get more and better special pricing on servers from manufacturers than you can on desktops. Also note that I listed the cost of acquiring 1,000 new thin clients as optional, simply because you can turn your existing 7-year-old machines into thin clients and use them until they break, and so on.

I did want to list the cost of acquiring 1,000 new thin clients because I was always criticized about ignoring that number. So, for new companies that are just being formed that want to deploy desktop virtualization and have no equipment I have taken that into consideration as well.

I have provided these numbers to ruffle some feathers and stir up some healthy conversation and invite comment to get everyone's perspective, I really would love to take the pulse of our readers as it pertains to desktop virtualization cost.

Posted by Elias Khnaser on 03/29/2011 at 12:49 PM


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