The excitement around virtual desktop infrastructure (VDI) is being tempered by the concern that VDI can't be cost-justified if it doesn't completely transform traditional desktop management - and by the belief that the only way to achieve this is with stateless desktops. The bad news is that truly stateless desktops won't be commonly available for at least another five years. But there is good news and that is, contrary to conventional wisdom, deploying virtual desktops and achieving state separation in client operating environments are not one and the same. In fact, although they will likely cross paths, they are fundamentally different objectives and should be viewed as separate endeavors. The reality is that enterprises can benefit from VDI today without capital investment or complexity, and without a completely stateless desktop, by leveraging cloud-hosted desktops delivered via desktops as a service (DaaS).

The State of State Separation
When you boil it all down, the argument for stateless VDI is that if an enterprise centralizes all of its virtual desktops onto data center virtual machines, it will end up with bloated images in its data center, much higher storage costs, and IT will have to manage those images just like it manages its physical desktops. Therefore, the thinking goes, if IT doesn't transform how it manages those images, i.e., via state separation technologies, the cost of VDI will be prohibitive.

To make sure we're all on the same page, let me define stateless desktops in the way that most people in our industry view it. A stateless desktop is a client operating environment (normally Windows XP or Vista) that can be built completely on the fly. That is, when a user logs in to such an environment, all of the components necessary to present a fully functioning desktop are brought together from different systems in real time. In addition, any changes a user makes to each of these components is stored somewhere on the network so that the user could theoretically move to a different system and receive the same exact experience the next time he logs on.

The four critical components or layers that make up stateless desktops (or any desktop environment for that matter) are:

• Client OS
• Applications
• User personalization
• User data

Unfortunately, in a traditional Windows desktop environment, these elements are all tightly coupled. In fact, the only layer that most IT departments have successfully managed to isolate is the user data layer. This is accomplished fairly easily by redirecting the ubiquitous Windows "My Documents" folder to the network. However, all of the three remaining layers are bound together by the Windows registry and are much more difficult to isolate. So although state separation is a great goal and there are some third-party solutions that attack parts of the problem, they don't bring us to the level of statelessness that is required for dynamically composed desktops and, in and of themselves, they are more like band-aids, each with its own integration costs and limitations.

Figure 1: Enterprise VDI beckons a serious look at state separation technologies because the enterprise bears the cost burden of the desktop hosting infrastructure, including storage

Why You Shouldn't Wait
We all know the economic situation is putting incredible pressure on IT to cut costs and operate with much greater agility. This is why VDI is so attractive, but also why many organizations feel they must wait for statelessness to adopt it. In fact, one could argue that in the case of enterprise VDI, since the organization is building and funding the implementation, state separation technologies such as application and profile virtualization are required to achieve a justifiable level of CAPEX, especially with respect to storage costs.

But, why would you wait when you can get these benefits now with cloud-hosted virtual desktops delivered by service providers who have the necessary infrastructure in place and can deliver the service levels enterprises need? DaaS decouples the entire OS environment from the device layer and moves it into a data center owned and operated by a service provider. By moving instances of Windows clients into a service provider's cloud, users are able to access them from anywhere they have a network connection with just about any device, and get their own personalized desktop down to the application level.

More important, with DaaS (as opposed to enterprise VDI), the economic model changes and CAPEX for the hosting infrastructure shifts from the enterprise to the service provider. Now, the cost of the infrastructure becomes an operating expense that enterprises normally pay as a monthly subscription. Organizations can onboard their first 100 or 1,000 users, leveraging their current desktop practices while offloading the CAPEX burden to the service provider. Therefore, holding off for stateless VDI because of costs concerns is no longer necessary - you can gain significant cost savings today by outsourcing cloud-hosted desktops.

How DaaS Meets Today's Needs
DaaS allows organizations to truly leverage a model I call "VCO" for "virtualize, centralize, optimize." VCO is based on the premise that, for most IT shops (perhaps with the exception of those with extremely mature desktop management practices), simply transforming physical PCs into server-hosted virtual desktops will not only lower overall desktop TCO but will also instantly bring about other benefits (i.e., security, agility, etc.) that have been previously unachievable. To put this in the context of Microsoft's Infrastructure Optimization model, a simple server-hosted desktop virtualization implementation can immediately take the targeted desktop infrastructure from a "Basic" state to a "Standardized" one.

Service providers are well equipped to deliver DaaS in the way enterprises need and at the cost structures they require. In order to address the storage footprint challenge inherent with hosted virtual desktops, these providers are implementing highly optimized storage infrastructure, which includes advanced thin provisioning and de-duplication technologies, specifically for their DaaS offerings. This, combined with economies of scale and operating efficiencies, allows most service providers to run hosting infrastructure at a much cost lower than the average enterprise. And that is what enables organizations to get started with DaaS while realizing compelling virtual desktop economics. A case in point is Pike County School District, which has just seven IT professionals supporting 25 schools and 9,720 students and faculty that are spread across 700 square miles. Pike couldn't have afforded to implement VDI itself. A cost-savings analysis comparing what it would have taken for Pike to build and deploy 1,400 centralized virtual desktops versus what it's costing with DaaS reveals 64% savings for the TCO of each workstation.

Figure 2: Cloud-hosted desktops (also known as Desktops as a Service or DaaS) alleviate infrastructure CAPEX for the enterprise and the associated pressure to seriously consider state separation technologies as a prerequisite for VDI

As I stated earlier, although stateless desktops aren't a pre-requisite for cloud-hosted virtual desktop deployments, they will eventually cross paths. In keeping with Microsoft's Infrastructure Optimization model, DaaS deployments will begin in what is comparably a "Standardized" state (1:1 stateful replicas of physical desktop environments that are managed using current desktop practices). Once enterprises get comfortable with their initial production cloud deployments, they can move along the maturity curve with state separation technologies - as they become available - to help optimize those virtual desktops, until they reach a more "Rationalized" or "Dynamic" state, where desktops can be completely composed on the fly. This will allow organizations to better take advantage of capabilities like dynamic pooling, where a single, static image is used as the source for deploying large numbers of virtual desktops. More important, it will allow enterprises to decrease the storage consumption of their cloud-hosted desktop environment, which will lower the service provider's hosting costs and ultimately result in a lower monthly cost for their virtual desktops.

The bottom line is this: the stateless desktop is a great goal, but it is not needed for VDI to be feasible or successful. If you want to begin realizing VDI's tremendous cost, security and flexibility benefits now, cloud-hosted virtual desktops as a service can get you there today.