Hosting Virtual Desktops: Tips for a Successful Outcome

If you've already virtualized the servers in your data center, desktop virtualization may seem like the next logical step. But businesses are finding that the benefits of hosted virtual desktop technologies are more nuanced. The advantages may be harder to quantify and harder to justify based purely on traditional ROI calculations.

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In addition, the 13,000 aging Windows XP thin clients in the stores are slow -- and users don't always like the look and feel of the thin clients. Managers can use these clients to connect to their applications by way of the Web-based user interface delivered by Citrix's XenApp.

The thin clients, which need a local browser to function, had already been updated to run Internet Explorer 7. But the limited compact flash memory in each machine couldn't keep up with temp file, swap space and other storage needs, while Web-centric programs like Flash bogged down the processors, Condit says.

Rather than issuing laptops to all 425 managers, Condit launched a XenDesktop pilot to improve performance from the stores' aging thin clients, since no local browser is needed, and to allow managers to securely access their virtual desktops and hosted data from any personal computing device, either at home or at work.

Jai Chanani, senior director of technical services and architecture, worked on the networking and data center infrastructure for the pilot. The project is, he says, a cost-avoidance play. The goal is to extend the life of the thin clients by presenting applications in a hosted Windows 7 environment, and avoid the need to invest in laptops and related endpoint security to protect corporate data.

There were some infrastructure issues to address. Rent-A-Center ended up switching to a different SAN and a new caching algorithm for its desktop virtualization back end. Bandwidth needs have also factored in. "It's not just the amount of bandwidth that desktop virtualization uses but when you are using it," Chanani says. The analysis is still in the early stages, but so far Rent-A-Center has needed to upgrade network links at 10% of its locations.

What users are allowed to do also needs to be controlled. For example, users can print at work but not from home, no data resides locally, and data cannot be copied to the user's local device or to a USB disk.

The project is on track to begin production deployments in the second quarter of this year.

-- Robert L. Mitchell

Of course, you can define desktop virtualization more broadly -- as a way to remove the Windows desktop environment from the physical PC and host it in the data center. This idea has actually been around since Microsoft introduced Terminal Services (now Remote Desktop Services) with Windows NT 4.0 back in 1996.

This software served up hosted Windows applications within terminal sessions, with Windows Server functioning as the underlying multiuser operating system. Citrix has extended that approach to include the presentation of a simulated Windows desktop operating system environment using RDS/Windows Server.

In both cases, the connection methodology is similar: A physical client (either a thin client or personal computer running special client software) exchanges keystroke, mouse and display information with a simulated Windows desktop running in a terminal session, or a Windows virtual machine residing on a back-end host.

The technology has improved since those early days of server-based computing. Today the performance is faster than ever, the user's virtual desktop can include whatever level of personalization that company policies allow, and in the RDS model, users can work within a complete virtual desktop environment rather than pick from a slim menu of virtualized applications.

Hosted desktop virtualization

You virtualize the entire Windows desktop environment, including applications, and host them in the data center. The user then interacts remotely with the hosted virtual desktop by exchanging keystroke, mouse and video screen updates with it.

Vendors offer two approaches based on the VDI model. Under the first option, the persistent VDI design gives every user his own virtual desktop that runs within a virtual machine on a back-end server. Each user gets his own virtual desktop that spins up from a unique, dedicated virtual machine image file containing a full install of Windows. The user owns the image, and any changes that he makes to it will be saved.

The second option presents a "nonpersistent" virtual desktop, which gets spun up on demand from a common "golden" image file and serves multiple users. When a user logs out, any changes made to the virtual desktop disappear.

Citrix presents a third option: Its "hosted shared virtual desktop" follows its XenApp/Presentation Server (server-based computing) model by offering up a simulated Windows desktop in an RDP session on Windows Server.

In cases where organizations were already using XenApp for application delivery, some IT departments have decided it would be more cost-effective to roll out XenApp as a platform for hosted shared virtual desktops rather than build a new infrastructure for VDI, says INX's Kaplan. Technically, however, he doesn't consider it to be a virtual desktop technology, since users are really running a shared Windows Server operating system, not a native Windows XP or 7 desktop operating system hosted within a virtual machine.

"While it is possible to do almost anything with XenApp that one can do with VDI, it can become very complex and burdensome. That is why it never took off as a mainstream desktop replacement solution despite the overwhelmingly compelling economics," Kaplan says. "At the root of the problem, you have Windows Server being used in a way it was never designed for."

Most of the Citrix virtual desktop deployments he's seen to date have used Citrix's XenDesktop to host nonpersistent VDI desktops, he says.

User virtualization: The next tech level

User virtualization brings desktop virtualization to the next level: separating users and the unique attributes of their work environment from both the client hardware and the virtual desktop image. The idea is to allow access from any Internet-connected device, be it a laptop, a tablet PC or a smartphone, and regardless of whether it's running a native Windows, Mac or Android operating system. That ability to achieve seamless portability across many different device types is available now but still evolving.

It is possible (although not always practical on smaller screens) to deliver a full Windows desktop -- or individual applications -- to a smartphone or tablet. Citrix offers versions of its Receiver client software for accessing virtual Windows desktops from both the Android and iOS mobile operating systems, as well as from PCs running the Windows, OS X and Linux desktop operating systems. The VMware View Client is available for the Mac, Windows and the iPad. (A Linux version of VMware View Client is available to OEMs such as thin-terminal manufacturers.)

While the client software generally supports devices running all of those operating systems, not every personal or mobile computing device will work flawlessly, nor will all the peripherals you attach to a thin client or personal computing device running desktop virtualization client software. It's important to check each virtualization software vendor's hardware compatibility list.

And in a cross-platform environment, not everything works together. For example, Citrix Receiver will stream applications only to Windows-compatible client hardware.

A lack of offline access has long been an Achilles' heel for virtual desktop technologies. Both Citrix and VMware recently introduced support for offline mode (VMware calls it "local mode"), which moves the virtual desktop image to the user's laptop and keeps it synchronized with the host version, through manual or automated updates, whenever the user has a connection.

But the technology is still maturing. "Our customers have not really adopted [offline features] yet, but we are looking at some pilots," says Scott Mayers, a principal director at Align.

-- Robert L. Mitchell

Going with the approach of nonpersistent virtual desktops saves on back-end management and infrastructure costs, since the approach uses a few golden image files rather than one for each user, and that takes up less networked storage space.

When users log out, their virtual desktops can be shut down. But it's more typical to keep the virtual desktops in a suspended state so that users can get up and running more quickly when they log back in. In fact, for nonpersistent virtual desktops, administrators may keep a pool of virtual machine sessions running or in a suspended state all of the time so that new users can get up and running quickly after logging in.

Before rolling out VDI, slow boot-up times on older PCs were one of the biggest user complaints, says Kevin Summers, CIO at Whirlpool. Now, early users of VDI are finding that they're up and running more quickly. "Employees aren't as frustrated," he says. [See sidebar.]

Application virtualization

You can virtualize individual applications -- using products such as VMware's ThinApp, Microsoft's App-V or Citrix XenApp -- and then deliver those into a virtual desktop or stream them down to a physical PC on demand and have them run locally. "Application virtualization is really software distribution done in a different way," Accenture's Slattery says.

The technique also promotes stability and eliminates application conflicts by isolating the application from other Windows apps as well as from the Windows operating system. No changes are made to the registry or other settings, so this mechanism can be used to, for example, run two versions of the same application side by side, or to avoid compatibility issues when running an old Windows XP application on top of the Windows 7 operating system.

User state virtualization

Finally, there's personalization: Virtualization of each user's personal settings, such as wallpaper and other configuration preferences, by storing that data in roaming user profiles or by using third-party tools from vendors such as AppSense or RES Software.

Some third-party tools can store more granular operating system and application settings and even one-off programs. Then the basics are loaded into a plain vanilla nonpersistent VDI session or a hosted shared virtual desktop session at runtime. The rest of the settings and information, such as Word macros, are streamed on demand as needed so users can get up and running more quickly.

"Roaming profiles give users the flexibility to roam between [devices] and preserve the user experience," says Gartner's Wolf.

Personalization tools offer the best of both worlds. They allow users of nonpersistent virtual desktops to maintain a customized work environment while administrators enjoy the efficiencies that come from maintaining a small group of shared virtual desktop image files. For this reason, says Gartner's Margevicius, "this will be the key technology for most customers over time."

"Customers ignore personalization at their peril," says INX's Kaplan. Not all users need a personalized desktop, he adds, but in some corporate cultures, deployments that fail to accommodate this demand won't succeed.

The lesson here, says Gartner's Wolf, is that many different pieces of operational software, including management tools and desktop antivirus software, will need to be tied into your desktop virtualization solution, so selecting the right products is critical. "There will be a high exit cost" for making the wrong choice and then having to backtrack, "so don't rush into a bad decision," Wolf warns.

Touchstone: Holding off virtualizing clients for now

Steven Porter, CIO at Touchstone Behavioral Health, recently completed a virtual desktop infrastructure proof of concept with VMware View. "We were very pleased with the results," he says. But he has decided to wait until some hardware incompatibility issues are resolved before he moves VDI into production mode.

"There's no real cost savings," he says, noting that additional virtualization and Windows licensing charges add $300 per laptop to his costs. Over the first three years, he says, "it's about a wash" when compared to what he pays now to run Windows on each physical machine. "But you gain in security and convenience. The real win is in end-user satisfaction."

Users will benefit from faster provisioning of desktops -- or re-provisioning when things go wrong. Other gains include greater reliability, better security and support for devices the user brings to work.

Porter says he'd like to get out of the business of owning hardware, most of which is laptops used in the field by Touchstone's staff. Many employees have their own computers and use the company laptop only to access electronic medical records and email. "That's 30% of my annual spend. I could divert that to projects that make more sense from a productivity standpoint," Porter says. "A lot of people are carrying my laptop during the daytime and pulling out theirs at night. They'd be more comfortable with one machine of their own choosing."

The technical issue holding back the project is the incompatibility of a USB-attached signature pad that's used in the field. The VMware View Client sees it as a mouse, and although the signature pad's manufacturer offers a "clunky" workaround, Porter feels that's too much to ask of his users, and he doesn't want to replace the signature pads. So he'll wait for a real solution.

More importantly, users in the pilot weren't sold on desktop virtualization technology either, although they would rather use a computer of their own choosing -- something that VDI enables. "They were ambivalent," Porter says. He eventually plans to roll out the virtual desktops. But before doing so, he says, he'll build a case study to show users "where they'll start seeing benefits, and that it will make their lives easier."

-- Robert L. Mitchell

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