VDI A Compelling Concept, But Early Adopters Must Be Nimble

Virtualization, a common feature in today’s data centre, is coming to a desktop near you; however, just what form it takes is still debatable. The VDI (virtual desktop infrastructure) technology and market landscape is fluid and rapidly evolving, with several architectures and usage models competing for pre-eminence. Adding to the confusion, many vendors have rebranded existing products with the virtualization badge, attempting to capitalize on the hype, says Aly Orady, CTO at Pano Logic.

Info-Tech analyst John Sloan says, “VDI is an area that’s generating a lot of interest and a lot of piloting,” although deployments are still low. In a recent survey of North American IT managers, Sloan found about 5% have already deployed VDI with about one-third at some point in the planning, testing, or piloting cycle. Most pilot tests are small at 20 to 30 users, but Sloan expects adoption to increase significantly in the next three years.

VDI Market Overview
Burton Group Senior Analyst Chris Wolf segments VDI solutions into server-hosted and client-hosted architectures that are largely self-explanatory. The former, the more common and accepted type of VDI, entails executing OS images on a central server and displaying on a local client. Server-hosted solutions range from those that deliver a complete, dedicated virtual OS to shared terminal services, what Wolf terms presentation virtualization. In client-hosted VDI, a VM image is typically downloaded from a central server but executed locally.
Sloan says several developments have led to increased enterprise interest in VDI. Foremost, the technology has advanced such that virtual desktops can now deliver a full desktop PC experience, including rich graphics, sound, streaming video, and control over local peripherals.
Sloan says that VDI is also being driven by a larger vision, primarily hyped by vendors, to decouple the OS desktop from a particular piece of hardware. As Wolf describes it, “The centrally located virtual desktop ensures that the user will see the same desktop, regardless of the endpoint device used for access—the desktop and available applications will remain consistent, regardless of the endpoint device.” This “liberated desktop” zeitgeist is a wonderful vision, according to Sloan, but he says current products don’t yet deliver on the promise. Yet Pano’s Orady counters that some vendors already offer complete virtual desktop solutions that integrate low-cost client devices, VM and user-management systems, and VDI-specialized network protocols and drivers that break the hardware-desktop link.

Hot New VDI Technologies & Trends
There are a number of innovative technologies that have improved VDI’s usability. An emerging, much-hyped technology with the backing of several key vendors is embedded client-side virtualization, which integrates a bare metal Type I hypervisor directly into a PC’s BIOS. Operationally like server virtualization, Wolf says this architecture opens up new usage scenarios, such as allowing laptop users to maintain a personal desktop VM, with their own software while simultaneously running a company-managed VM, which is a prerequisite for connecting to the internal LAN. A variant is the BYOPC (Bring Your Own PC) scenario in which users purchase and manage their own personal PCs running both enterprise OS image and personal OS image, with complete isolation between personal and corporate applications and data.

Although server-hosted VMs have largely stolen the limelight from shared terminal services, it comes at the cost of thicker, more costly end points and increased server load. Some companies have eschewed the “PC baggage” of desktop thin clients and instead offer what Orady calls a "zero client"-essentially a networked concentrator that connects local peripherals with a server-based VM. Zero-client architectures provide the performance and user experience of a PC by tightly integrating a small, simple access device, a custom communication protocol for routing video and peripheral signals, with their virtualization software.

Planning, Deployment & ROI
As might be expected, analysts and vendors disagree about VDI’s enterprise readiness. Wolf sees the market as in flux and still immature and recommends waiting until mid-2010 before widely adopting VDI. Sloan agrees, not expecting large-scale enterprise deployments until the 2010 to 2012 timeframe. While he admits enterprises aren’t going to wholesale replace PCs with thin clients, Orady says full end-to-end VDI solutions are available and that enterprises should deploy them to that portion of their desktops causing the most administrative pain. He sees VDI following a gradual adoption curve similar to that traversed by server virtualization, with enterprises initially converting 5 to 10% of the most propitious desktops, such as those in training rooms, manufacturing floors, hospitals, or call centres, and increasing VDI penetration as users and IT becomes more comfortable with the concept.

Given plummeting PC hardware prices, most VDI architectures don’t result in capital expense reductions-in fact, Calvin Hsu, director of product marketing at Citrix, cautions that VDI may necessitate costly network and storage upgrades. The more significant financial benefits come from reduced management and administration (up to 20% lower by Burton Group’s estimate), lower power consumption (when using thin clients), and lengthened hardware upgrade cycles (when reusing old PCs as VDI access devices). These must be balanced against the cost for backend VDI servers, storage, and software.

Burton’s Wolf concludes that "Desktop virtualization has come a long way in a relatively short time; however, the relative immaturity of desktop virtualization platforms and the rapid improvements in networked storage for virtual desktops are both good reasons to delay implementation wherever possible."