WALTHAM, Mass. -- Desktop virtualization seems to be the most natural path for Windows 7 upgrades in shops that
have already successfully virtualized servers, but desktops aren't nearly as easy to virtualize as servers because end-user PCs are individualistic.
A diverse end-user community calls for a variety of desktop virtualization technologies. And so we have client hypervisors, workstation virtualization, application virtualization or virtual desktop infrastructure (VDI).
This inability to standardize virtual desktops makes desktop virtualization difficult for IT pros who want to move away from the old paradigm of buying pallets of hardware for a Windows upgrade, said Brian Madden, a desktop virtualization expert and blogger who hosted the seminar "Desktop Virtualization: What it means in 2010" here last week.
"Windows 7 is here, but the desktop virtualization technologies aren't entirely here, or we simply aren't comfortable using what's here," Madden said. "But the clock is ticking, and we have to make some decisions now."
In fact, most attendees at the seminar indicated by a show of hands that they use Windows XP and will upgrade to Windows 7, but they were undecided on whether to virtualize desktops or stick to the traditional upgrade process.
In reality, many shops will do both.
For instance, one IT administrator for a town in Boston's suburbs said she virtualized servers with a hypervisor from VMware and is testing VMware View for town employees such as firefighters, who move from station to station and need desktop access from wherever they are. But since most employees are stationary much of the time, her Windows 7 rollout will be a mix of desktop virtualization technologies and traditional desktops.
While that hybrid approach isn't ideal, it provides a way to manage both remote and local desktops and offset hardware upgrade costs, said the administrator, who requested anonymity.
Those advantages are driving desktop virtualization adoption in many IT shops, despite the complexity.
"Windows 7 is being used as an excuse from IT to senior management," said Todd Knapp, CEO and founder of Providence, R.I.-based virtualization consultancy Envision Technology Advisors. "The real motivators are built around extending hardware refresh cycles, simplifying management and gaining greater control over end-user environments."
Desktop virtualization conundrum
Server-based VDI products, such as Citrix XenDesktop or VMware View, let IT pros manage desktop images from the data center, which aids desktop security and manageability but also has limitations.
One problem with the server-based computing approach is the lack of offline support unless there is a client hypervisor added to the mix. Citrix's bare-metal client hypervisor, XenClient, is now in beta and has to be manually installed into client devices to support offline virtual machines (VMs), and VMware View 4.5 supports offline access via "local mode" in the Premier edition of the product.
Server-based VDI costs can mount thanks to bandwidth constraints and storage requirements. VMware added tiered-storage support in the latest version of View, and third-party vendors also offer to solve storage issues. For instance, Atlantis Computing offers add-on software that consolidates desktop images and offloads I/O-intensive Windows operations from VDI storage to reduce storage strains and costs.
In addition, IT pros should review a number of application virtualization products on the market that they could add to their virtual desktop environments to avoid application conflicts.
In fact, Envision Technologies' Knapp said he only deploys hybrid environments that deliver a full desktop operating system coupled with virtualized apps. Some are streamed, some are not.
Unfortunately, the layering doesn't end there. To provide end users with personalized desktops, enterprise IT needs to add profile management software from third-party vendors such as Liquidware Labs, triCerat or Unidesk. Citrix XenDesktop 4 includes profile management, but its functions are limited.
Instead of all that layering, some shops choose workstation virtualization, which offers the management benefits of server-hosted virtual desktops without the confusion and infrastructure costs. With workstation virtualization offerings, a virtual machine (VM) runs on a local desktop OS, abstracting all of the desktop applications and data. This approach provides offline support, but it runs locally, so the level of security that server-hosted VDI provides isn't there.
Regardless of whether you choose one desktop virtualization technology or a combination of many, there are five capabilities that should be "fully baked" for a desktop virtualization project to really work, Madden said.
One of the most important is support for high user density ratios to keep infrastructure costs down, and IT pros should not take vendor ratio estimates at face value. There are a lot of variables that determine density ratios, so IT pros should test VDI products using real workloads in their own environment, he said.
For a VDI rollout to succeed, it needs to include thin provisioning, offline support and user profiles (or personalities), and vendors need to improve remote display protocols so end users can do all the things they do on a traditional PC without performance degradation.
Citrix improved its ICA protocol with HDX, VMware introduced PCoIP, and Microsoft improved its Remote Desktop Protocol this year, but there is room for improvement to all, Madden said.
He predicted that all of these capabilities will be available by summer 2011. In the meantime, IT pros should ascertain ways to use virtual desktops, including the best candidates for virtual desktops, the applications those users need, and whether or not those applications can be virtualized.
In addition, Madden recommended figuring out the network, storage and client device requirements. Enterprises should pay attention to the reasons VDI projects fail to avoid those pitfalls.