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For all of the heavily hyped advantages of VDI, there are still a slew of drawbacks, concerns and challenges to successfully implementing and supporting the technology.
VDI and desktop virtualization aficionados often sing the technology's praises, but implementing it isn't a walk in the park. It's hard to get a deployment off the ground, and some projects never make it out of the pilot or proof-of-concept phases. Even when companies do roll VDI out, it doesn’t always succeed.
Many people can -- and do -- gripe about VDI challenges. Here are the seven most popular complaints:
One of the main selling points for VDI is the theoretical nirvana of a centrally controlled and administered desktop that should be -- if implemented correctly -- much more secure than traditional standalone desktops running on end-user computers. But at what price and complexity do we achieve that theoretical nirvana?
In most circumstances, if your VDI back-end infrastructure suffers an outage, the majority of your users are unable to perform the work that generates revenue and keeps companies running. As a result, your servers, storage and network infrastructure must be highly fault-tolerant. That requires clustered servers, a highly available storage area network and redundant network links that mitigate the risk that a single point of failure can bring your VDI environment to a standstill. Of course, high-availability platforms have been protecting critical applications for many years. But the complexity of creating such a redundant, fault-tolerant environment is not trivial, and is a consideration for any company looking at doing VDI.
Direct -- and indirect -- costs
One of the first advantages of VDI that pundits and vendors touted was that it can save companies money in much the same way that virtualizing servers has become a cost-saving standard. But the equation turns out to be quite different in the VDI world. Back-end infrastructure must be fully redundant, expandable and fault tolerant. That can be an expensive proposition, depending on how many end users you support.
There are also costly challenges relating to application and operating system licensing. And don't forget the unseen expenses that come from implementing a new application or environment: Change tends to make people less productive while they adjust to new features and restrictions. Expect some turmoil and confusion as you roll VDI out to any installed user base.
Each time you establish a connection from your local computer to your VDI environment, you are served a pre-built image of the operating system, applications and custom user settings. Assuming that end users all have similarly configured desktop or laptop computers, those images should run on most computers in an organization, though certain special cases may require custom images. But what happens when your users clamor for VDI support for mobile devices?
I can connect to my company's VDI environment with a tablet or smartphone, but I obviously cannot run a Windows 8 desktop image on those devices. Some VDI technology allows you to support smartphones and tablets, but it is an issue that must be addressed in the modern, bring your own device (BYOD) world.
Data center density
There's no getting around the fact that VDI is a resource hog in the data center. As the density of VDI racks and appliances continues to go up, so does the underlying need for power, cooling and network capacity in the data center.
Implementing resource-intensive services such as VDI is really about chasing data center bottlenecks until you have some marginal balance between cost and performance. If the data center network connection to the Internet is a VDI bottleneck, you can always install 20 or 50 or 100 redundant Internet links, but that will likely cost more than the entire VDI project. There is a delicate balance between providing enough power, cooling and network capacity to adequately run VDI while still keeping infrastructure costs under control.
Because of the centralized control over desktops and applications that come with VDI, virtual desktop security should always be tighter. The keyword there is "should."
Centralized control offers the opportunity for a very secure desktop environment, but VDI admins must carefully construct that security through management of end-user policies, physical security of the VDI back-end environment, and the ability to disable hardware and software that leaves traditional desktops at risk. Anti-virus (AV) scanning can also be centralized in a VDI environment, eliminating the need to run AV software and regular scans on local computers.
VDI admins require a different skillset than traditional administrators because VDI is totally dependent on a tightly-integrated set of infrastructure technology and services. As your company considers transitioning to a VDI environment, your network, server, application and storage admins absolutely must work in unison for VDI to work as designed.
This dynamic can be difficult to instill in various IT teams that may not be accustomed to working closely with admins from other teams. Sometimes groups aren't willing to work with other teams. No problem: You can always hire someone with the requisite VDI admin expertise, right? In an ideal world, companies implementing VDI would simply search the vast pool of available IT talent for someone with VDI expertise, but VDI is still new enough that finding the right person can be expensive and exasperating.
The laws of supply and demand will likely keep salaries for VDI admins elevated for the foreseeable future.
Degraded desktop performance has always been one of the criticisms leveled at VDI technology. Great strides have been made in improving performance and increasing the desktop density for back-end VDI components, but there are still performance challenges yet to be solved.
Even with VDI performance increases, there are still certain types of users for whom VDI may simply not be a viable alternative. For example, large files such as graphics and databases must be downloaded to the user's machine each time they begin work, and must then be uploaded back into the virtual infrastructure when the user is finished. Considering the large amount of network traffic generated by VDI, these users may find that they require a traditional, locally-installed desktop with local storage of user files to get their job done.
The VDI community has made leaps and bounds in the installation, tuning and administration of virtual desktops over the last three or four years. Many of the early roadblocks to successful VDI implementations have been eliminated or addressed via VDI vendor education, VDI community discussions and refined project-planning techniques.
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