Early versions of desktop virtualization completely removed the operating system from individual PCs and brought it to the data center, leaving just the input and display at the user's desk. The latest versions of desktop virtualization, dubbed desktop streaming, make full use of an individual PC's power for much of the processing. Each user has a complete operating system and application image running in a virtual machine on their desktop. The arrangement maintains the benefits of central management without dispensing with the desktop's power.
The main benefit of desktop virtualization is that it gives administrators the ability to provision PCs and other client devices with software from a central location. Administrators can deploy standardized desktop images to a variety of users, such as mobile workers who move in and out of the network, employees at branch offices and contractors. Out-of-compliance virtual machines can be quarantined, and those users can be forced to update their system. Desktop virtualization reduces the cost of on-site support, since an administrator can update the patch server, which will in turn automatically update clients when they call the application. The capacity to centrally lock down corporate environments while reducing costs is attractive.
Desktop virtualization may sound like terminal services, where servers run the applications and give users remote access. It is quite different, though. Servers host an entire desktop environment specific to each user. To address load-balancing or fail-over issues, virtualization also adds the ability to move desktop environments and hosted applications as needed. Application streaming provides even greater flexibility: a basic operating system image can be created, and then individual images for each application can be combined as needed on the fly. Application streaming greatly reduces the number of unique desktop images that are needed. It also gives a far better idea of which application licenses are really necessary.
Virtualization does require administrators to think differently about common tasks. A server that goes down can take multiple users down with it. Disk usage needs to be monitored carefully, as users will share the same drive space. By its nature, the technology adds complexity and requires news skills. And be aware that although virtualization makes locking down a network environment that much easier, it doesn't eliminate the threat posed by low-level malware on the host machine, such as keyloggers or rootkits.
This was first published in April 2008