A desktop virtualization primer

Most IT leaders are familiar with server virtualization. Less familiar, however, is desktop virtualization, where similar principles are applied to end-user desktop operating systems and applications, presenting a different set of benefits and caveats.

Most IT leaders are familiar with server virtualization. Rather than provisioning and maintaining hardware for every application, the underlying server hardware is virtualized, allowing it to be quickly provisioned, moved, or allocated different resources, all without turning a screwdriver or buying any new hardware.

This process makes IT more fluid, since managing servers is now largely a matter of mouse clicks once the infrastructure is in place. Less familiar, however, is desktop virtualization, where similar principles are applied to end-user desktop operating systems and applications, presenting a different set of benefits and caveats.

Virtualizing the PC

Like their data center counterparts, virtual desktops run in a hypervisor in the data center, communicating with a client application on a PC or thin client. Conceptually similar to some of the “hosted desktop” solutions of the past like Windows Remote Desktop, desktop virtualization can provision a full and isolated desktop for the end user, which can then be provisioned, moved, and managed like its data center counterparts.

Additionally, virtual desktops can leverage snapshotting technology, allowing an entire department’s or company’s virtual desktops to be based on a single standard image, which can be patched and updated once, rather than having to manage thousands of end-user PCs.

The major players in the desktop virtualization space are similar to those in the data center, with Citrix, Microsoft, and VMware staking claims to this emerging segment of the virtualization market. What’s interesting is that, unlike the data center, you need not select a single-vendor to provide all the pieces of a virtualized desktop environment.

If your organization has already committed to VMware and the vSphere series of data center products, you can happily run your virtualized desktops within a VMware hypervisor, using a Citrix product to provision end-user desktops and virtualized applications while a virtual desktop-aware Microsoft management tool manages and updates virtual desktops.

Benefits and drawbacks

The benefits of desktop virtualization initially seem extremely compelling. Rather than chasing down thousands of end-user devices, the OS and applications sit happily (and securely) in the data center, with a standard set of drivers and applications. End user complaining about performance? Click a few buttons and he’s got a faster processor and more RAM allocated, versus bringing in his hardware and ordering parts.

Furthermore, virtual desktops disconnect end-user hardware from corporate software standards, allowing users to run their Windows desktop on an Android tablet, or work happily on the Mac or Linux box they prefer, without IT having to support those environments or find corporate software that works there. Virtual desktops allow for the ultimate in BYOD environments, allowing users to bring nearly any device to the workplace, connect to a firewalled network, and then securely perform their work on a virtual machine residing in the data center.

Individual applications can even be virtualized, allowing a standard image of your ERP client to be available to those who need it, without requiring software installations and updates on a client PC. In high-security environments, all data remain in the data center, with the client PC running the modern equivalent of a dumb terminal. New thin client hardware is even available with no moving parts or local RAM.

Like any new technology, desktop virtualization is not without its challenges. For decades end users have grown accustomed to being able to work on their devices in a limited fashion when networks or applications are down. I’m writing this very article from 30,000 feet, with nary a WiFi network available. In a fully virtualized environment, this is impossible. Even for non-mobile users, virtual desktops create the ultimate single point of failure. If connectivity to the data center is severed or there’s a maintenance or performance issue, rather than only affecting corporate applications, you’ve left your end users with a blank screen, and paper and pencil.

Virtual desktops also move a massive computing load into the data center. While most desktop users rarely stretch the legs of modern CPUs, you’re centralizing a vast amount of resources that require careful sizing. We’ve all seen loads peak on applications when the workday starts; now imagine that your servers will be required to help boot thousands of virtual desktops each morning and process the latest dancing cat YouTube sensation after lunch.

Like server virtualization, centralizing this demand does offer a mitigation path in that you can quickly allocate and tweak loads across the backend infrastructure, providing a mitigation strategy against these peak volumes.

Now that we’ve uncovered some of the pros and cons of this technology, in the next article I’ll review some of the key players in the virtualized desktop space.