Hosting virtual desktops: Tips for a successful outcome

Be prepared for a long road; the technology requires a significant buildup of servers and other infrastructure, among other things

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Virtual desktop architectures, which transmit graphics as well as keystroke data and mouse clicks, can tax your network, says Slattery. "If you have a lot of branch offices or home users who don't quite have the network performance you need, that may guide your decision." On the other hand, if you already have a virtual server environment and the network to support it, you may not need to invest as heavily in new switches and other networking equipment.

Kevin Summers
Whirlpool is using virtual desktops to help improve customer service -- specifically, improved reliability and flexibility, says CIO Kevin Summers.

"Storage is also a concern because you're moving off relatively cheap disk on the desktop to a back-end SAN," says Align's Mayers. "Your cost per gigabyte is increased."

Management tools are a still a work in progress, says Gartner's Wolf. "I ask clients, if they have to add another five tools to manage their virtual desktop environment, which ones are they able to take away that they used previously? Typically, the answer is none." The most popular tools may be able to plug into enterprise management frameworks from Microsoft, IBM and others. But the integration work is unfinished, Wolf says.

Antivirus software is another hidden cost, says Wolf. Installing traditional desktop antivirus software into each virtual machine taxes CPU cycles and disk I/O. While McAfee and Trend Micro now offer special-purpose virtual antivirus appliances, most IT organizations are waiting for the second-generation product before committing to it, Wolf says.

"The net result will be that you will be running fewer desktops on physical servers than you planned for, and you can imagine how that snowballs," Wolf explains. "That means more servers, more storage ports, and the cost of supporting virtual desktops can go up as a result."

In other words, if you're running fewer virtual desktops on physical servers than you had planned because of the antivirus software and other gear needed to support those desktops, that means you'll need more physical servers. But there's no rule of thumb for this in terms of X number of servers to support Y number of virtual desktops, because there are too many variables, such as the number of applications installed in the image.

Slattery is less concerned about management tools, storage and other infrastructure, which IT already knows how to deploy and manage efficiently. "The biggest challenges come down to licensing," he says.

Check your licenses

IT needs to factor in licensing costs for virtualization software and infrastructure management tools, but the wild card is what it will cost to migrate all of those Windows licenses off physical hardware and onto virtual desktops.

The total cost depends on your existing licensing agreement. Users already paying for Microsoft's Software Assurance for Windows get the rights to create up to four Virtual Desktop Access (VDA) images for a given user's Windows-based desktop, laptop or tablet computer.

"Any device covered by Software Assurance gets the grant rights. Others, such as thin clients, require the purchase of a separate VDA license," says Gavriella Schuster, general manager of Windows product development.

For users without Software Assurance or who want to use a thin client, an iPad or a device other than a Windows-based desktop, laptop or tablet, it's a different matter. "Microsoft does not permit the Windows desktop operating system to be licensed away from the physical machine," says Margevicius at Gartner. "It requires you to purchase a separate VDA license [per virtual desktop], and that's $100 per year" per virtual desktop. (Microsoft's RDS client licenses, required for XenApp, cost a bit less -- in the range of $75 to $85 for a perpetual license. This is because the user is sharing a single instance of Windows Server rather than running a full instance of the Windows desktop operating system, Microsoft's Schuster says.)

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