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.