How to Implement Green Data Centers with IT Virtualization

Client virtualization

A great potential in energy savings is client, or desktop, virtualization. Various studies have estimated energy savings of more than 60 percent by using client virtualization. Client virtualization—often called thin-client computing—is not a new concept and goes back at least 15 years. In fact, thin-client computing, where the server does all of the computing, is similar in concept to the terminals we used to connect to the mainframe before the advent of the PC.

Benefits of client virtualization

The significant benefits of client virtualization and the use of thin clients are the low cost of ownership (including lower energy use), security and reliability. Boot image control is much simpler when only thin clients are used—typically, a single boot image can accommodate a very wide range of user needs and can be managed centrally. Thin-client technology can be a significant benefit, for example, in supporting help desks where everyone at the help desk needs to access the same server applications.

Risks of client virtualization

The major risks to moving to thin-client technology include the loss of flexibility when moving from a thick client. Our laptops are thick clients and give us the flexibility to use them anywhere—with or without a network connection. Also, a server that supports thin clients must have a higher level of performance since it does all of the processing for the thin clients. Thick clients also have advantages in multimedia-rich applications that would be bandwidth-intensive if fully served.

But the major risk in moving to thin clients is loss of flexibility. On some operating systems (such as Microsoft Windows), software products are designed for personal computers that have their own local resources; trying to run this software in a thin-client environment can be difficult.

So, client virtualization through thin-client computing gives us very significant benefits but there are also concerns. A good place to start with client virtualization is the help desk, where the benefits usually greatly outweigh the concerns.

John Lamb is a Senior Certified IT Architect with IBM Global Services in New York. He has authored or co-authored numerous technical papers and articles, as well as five books on computer technologies including the May 2009 book: "The Greening of IT: How Companies Can Make a Difference for the Environment." John holds a Ph.D. in Engineering Science from the University of California at Berkeley. He can be reached at jlamb@us.ibm.com.