One of the major trends that is currently taking place in IT is that many organizations that have always operated traditional client / server networks are beginning to look into using Virtual Desktop Infrastructure (VDI).

In case you are not familiar with VDI, VDI works similarly to a thin client computing environment. The one thing that sets VDI apart from a normal thin client environment is that VDI solutions make use of virtualization. When users connect to a terminal server, a connection broker matches the user’s session to a virtual machine running a desktop operating system.

Although the initial VDI implementation process can be a major undertaking, organizations are finding that making use of VDI can lower the total cost of ownership for desktop computers.

There are several reasons why this is the case. For starters, VDI solutions typically make use of terminal sessions. That means that the user’s desktop computer is acting as a thin client. The primary desktop operating system and software is running within a hosted virtual machine.

Organizations using VDI often find that because desktop hardware is only acting as a thin client, the hardware’s useful lifespan is extended because the desktop hardware does not have to keep pace with the demands of the latest desktop operating systems and all of the bloated applications that run on it. Likewise, some organizations find that their costs are also reduced because they are able to purchase low end, commodity hardware for their users rather than well-equipped PCs.

Another way in which VDI solutions may decrease an organization’s total cost of ownership is in reduced maintenance costs. One of the problems with traditional desktop environments is that over time desktops tend to diverge from the configuration baseline. Likewise, desktop PCs may become infected with malware or have critical system files damaged in other ways.

VDI solutions make use of virtual PCs. Because of this, it is possible to ensure that each user receives a desktop that is in a pristine state every time that they log in. Every time that a user logs out of a virtual machine, the virtual machine is rolled back to a pristine state.

Given the benefits of VDI, some may wonder why VDI is only now beginning to gain mainstream acceptance. The primary reason for this has to do with the fact that although VDI has been around in one form or another for several years, the technology is only now beginning to mature. While this fact may spur VDI adoption, it has also lead to another problem.

The problem is that because VID relies on virtualization, a VDI solution is only as good as the underlying hypervisor. If the hypervisor that is being used has performance or stability issues, then those issues will most likely manifest themselves through the end user’s virtual desktop sessions.

I will be the first to admit that Hypervisors have been around for several years, and that they are a reliable technology. However, hypervisor technology is still evolving. For example, Service Pack 1 for Hyper-V 2008 R2 introduces a new dynamic memory feature that will allow organizations to increase the density of virtual machines running on a host by allowing memory over commitment. My point is that today’s hypervisors will most likely be completely inferior to the hypervisors that will be available a year and a half from now. Furthermore, it is entirely possible that in that time frame today’s leading hypervisor vendors could be upstaged by a new startup with a radical new approach to hypervisor technology.

So what does all of this have to do with VDI? As I said, a VDI deployment is only as good as the underlying hypervisor, and hypervisor technology is constantly changing. The problem is that most of the vendors who offer VDI solutions are trying to establish market dominance by designing their VDI software so that it will only work with their hypervisor.

This approach makes perfect sense for a software vendor. Requiring customers to use the vendor’s own hypervisor reduces support costs, and it helps to increase revenues because customers are unable to use hypervisors from other vendors. From the customer’s prospective however, this is something of a raw deal because it locks them into using a specific hypervisor solution, rather than being able to take advantage of new hypervisors from other vendors as they become available.

Given all of the recent advancements in hypervisor technology, and the fact that hypervisor innovation shows no signs of slowing down, it may be prudent for organizations that are considering a VDI deployment to look for a vendor that takes a hypervisor agnostic approach. By doing so, an organization would be free to switch hypervisors as better hypervisor technology becomes available, without having to replace their entire VDI infrastructure in the process.

At the moment, I only know of one vendor who offers a hypervisor agnostic approach to VDI. 2X VirtualDesktopServer ( is designed to work with a number of different hypervisors including Microsoft Hyper-V, VMware ESX, ESXi, and vSphere, Parallels Virtuozzo Containers, Citrix XenServer, Sun VirtualBox, Windows Terminal Services / Remote Desktop Services, and the list goes on.

Another nice thing about 2X’s Virtual Desktop software is the pricing structure. Many VDI vendors require organizations to license their wares based on the number of connections to the server, or based on the number of virtual machines that are being hosted. 2X VirtualDesktopServer is licensed on a per server basis, with each server supporting an unlimited number of connections and an unlimited number of virtual machines.


In my opinion, using a modular, hypervisor agnostic approach is the only way that an organization can truly hope to future proof their VDI deployment. While there is little doubt that organizations using proprietary solutions will be able to eventually upgrade, they become locked into using a single vendor’s products and risk not being able to take advantage of hypervisor advancements that come from other vendors.

About Brien Posey

Brien Posey is a freelance technical writer who has received Microsoft’s MVP award six times for his work with Exchange Server, Windows Server, IIS, and File Systems Storage. Brien has written or contributed to about three dozen books, and has written well over 4,000 technical articles and white papers for a variety of printed publications and Web sites. In addition to his writing, Brien routinely speaks at IT conferences and is involved in a wide variety of other technology related projects. For more information, please visit:

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