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Virtual Desktop Infrastructure, also known as VDI, is one of those emerging technologies that inherently just seems like a good idea. After all, replacing all those aging, physical desktops with low power “thin client” devices, and using shared datacenter resources to run virtualized desktops just has to be more economical. Doesn’t it?

The short answer is “maybe.” It might actually save you some money, but it could actually cost you more than a traditional desktop refresh. If your VDI implementation creates virtualized desktops in your datacenter, but you still have one virtual desktop for every physical desktop that you replaced, you probably are spending more money. The reason for this is really two-fold.

First, your virtualized desktops are now running on server class hardware in the datacenter. It is great that the VDI are running in the datacenter, where they can more easily be secured, controlled, etc., and you can happily list this as a positive reason for implementing VDI. However, when it comes to laying out the numbers in your budget for the CFO, the server class hardware is more expensive than desktop hardware. Server class hardware often includes redundancy not often incorporated in physical desktop hardware – redundant power supplies, redundant disk storage (local, NAS, or even a SAN), and redundant (and often higher speed) network access (NICs, ports, and switches).

Secondly, your end user still needs some type of device to interact with the virtual desktop in the datacenter. You might be able to get by with software that “converts” the old desktop systems into “thin client” devices. This is typically a low budget option, but it assumes that the old devices still have any appreciable useful life remaining, even if they are just functioning as a thin clients instead of full featured workstations. At the other end of the spectrum, replacement devices could be new low end workstations, tablet devices, or possibly purpose-built thin client devices. If you haven’t priced these thin clients, many of them cost as much as a decent workstation, and tablets can easily cost even more. (Have you priced a Microsoft Surface, or a new iPad???) Thin client devices probably have a longer life expectancy than a typical workstation, but since the cash outlay is still there, you may not save any money here either.

Okay, you can make a case that because desktops are running in the datacenter, security is improved, and therefore risk is lowered. Lower risk equals lower chances of unplanned costs (lost or stolen data, etc.), right? Because virtual desktops allow for centralized administration and updating, you can claim that management costs are lowered as well. Realistically, are you going to be able to cut staff as a result? If not, everything we just cited are “soft costs” – we really can’t show hard savings. The bottom line here is that if you are trying to cost justify this to your CFO, chances are he/she only want to see hard cost savings. If you propose doing what we have depicted above, you might as well cross VDI from your proposed budget now.

If you really need to cost justify a VDI project, using only hard cost savings, you have to do one simple thing – reduce quantities. If you can reduce the quantity of desktops (virtualized) by doing things like creating a pool of virtual desktops, and letting users “check out” virtual desktops from that pool on an “as needed” basis, you might actually find some cost savings. There are products in the VDI space that may also reduce quantities for you.

One example of this is a storage de-duplication product. All of these virtual desktops are now consuming your expensive SAN storage now, but many of those SAN storage systems now include the ability to “de-dupe” the data that is actually stored on disk. Since these desktops are inherently similar, there is going to be quite a bit of duplication between them. After all, they may well all be running the same operating system, use the same installed software, etc.

Another example of this is disk virtualization. Both VMware View and Citrix XenDesktop can use hypervisor level cloning technology to create multiple virtual desktops from a single desktop image. This significantly decreases storage requirements for virtual desktops over the just adding up the footprint of all the desktops. Products like Citrix Provisioning Server take this a step further in that they allow for thousands of virtual desktops to boot from a read-only virtual disk. The only disk based footprint with this solution is a cache for changes that occur while the virtual desktop is running. Going a step further, Unidesk has introduced their layering technology. Essentially they allow for a virtual desktop to be custom “assembled” by picking up virtual disk “layers.” In their system, each layer can be a component – such as the operating system, or an application or application set (such as MS Office). Administrators can then choose the layers to use together to provide a virtual disk for a virtual desktop configuration for a group of users.

Of course, as you increase the use of tools you use to reduce the quantities mentioned above, you have increased complexity and cost of the infrastructure. The key is to strike that happy balance where you actually do find a cost savings. Investing money up front to cost justify your business case for VDI can make the difference between actually saving money for your company and finding a new job.

Brian E. Holzer, CCE-V, CCP-N, CCP-M, CCA-N (former CCI)
Sr. Architect
Innovative Integration, Inc.

About Brian Holzer

Brian is a seasoned IT consultant (pre-sales, delivery and marketing) with experience across many industries (healthcare, financial services, communications, manufacturing, education, government, utilities, professional services, etc.). He is a former IT Director, Assistant Professor with Purdue University, and an application developer.

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