The case for and against virtualized desktops

Insightful analysis by consultants Steve Taylor and Jim Metzler, plus links to the latest WAN news headlines

As we stated in the last newsletter, the goal of cloud computing is extremely clear. That goal is to make a significant improvement in the cost effective, elastic provisioning of IT services. This newsletter will explore how desktop virtualization supports that goal and will identify some of the performance problems that are associated with desktop virtualization.

Cloud computing: Hot technology for 2009

There are two primary forms of desktop virtualization. One form is commonly referred to as server-side virtualization and it involves users accessing applications that are hosted at a central site. The other form is commonly referred to as client-side virtualization and it involves applications that are streamed on-demand to client devices. In both of these models, the application is virtualized in the sense that it appears to be installed on the client device when that is not actually the case.

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As we stated in the last newsletter, the goal of cloud computing is extremely clear. That goal is to make a significant improvement in the cost effective, elastic provisioning of IT services. This newsletter will explore how desktop virtualization supports that goal and will identify some of the performance problems that are associated with desktop virtualization.

Cloud computing: Hot technology for 2009

There are two primary forms of desktop virtualization. One form is commonly referred to as server-side virtualization and it involves users accessing applications that are hosted at a central site. The other form is commonly referred to as client-side virtualization and it involves applications that are streamed on-demand to client devices. In both of these models, the application is virtualized in the sense that it appears to be installed on the client device when that is not actually the case.

The fact that hosted and streamed applications can both be sourced from a single application repository dramatically reduces the cost and complexity of managing applications and desktop environments. For example, once desktops are virtualized it is easier for the IT organization to deploy new applications and/or application upgrades. It also makes it easier to provision new desktop systems and secure systems and data from intrusions.

Application and desktop virtualization, however, can lead to performance problems, as all of the data that supports the applications and/or the desktops has to transit the WAN from one or more data centers to the user. Protocols optimized for hosted application virtualization (ICA and RDP) are more efficient in their use of the WAN than are protocols such as Common Internet File System. However, network latency can cause the performance of these protocols to degrade. This can have a very negative impact on tasks such as a user moving his/her mouse around a computer screen.

Compared with hosted applications, streamed applications are far less efficient as they typically use the same inefficient protocols that are native to the application. Furthermore, streamed applications create additional challenges for the IT organization because of the large amount of data that must be transmitted across the WAN when the application is initially delivered to the branch.

We would like to hear from you. Have you implemented desktop virtualization? If so, were you pleased with the results? Write to us and let us know. Also, we are performing a survey. If you have a few minutes to fill out the survey, it will help us to understand what is driving and inhibiting organizations relative to implementing desktop virtualiztion.

Read more about lans & wans in Network World's LANs & WANs section.

Steve Taylor is president of Distributed Networking Associates and publisher/editor-in-chief of Webtorials. Jim Metzler is vice president of Ashton, Metzler & Associates.