At its simplest, virtualization on the application server side reduces hardware costs by letting one server provision multiple desktop clients, rather than having one server per desktop client, says John Humphreys, an IDC analyst. And virtualization also adds the ability to move desktop environments and hosted applications as needed for load-balancing or fail-over. To make existing terminal services and blade systems work with virtual machines, established providers such as Citrix and ClearCube have developed broker technology to let IT manage the mapping to virtual resources.
Citrix, ClearCube, and Wyse Technology now support the use of VMware and Microsoft virtual machines on blades and other application servers. VMware also offers VDI (Virtual Desktop Infrastructure software), which makes server-hosted virtual machines accessible to users through the RDP (Remote Desktop Protocol).
Bell Canada uses VDI to provision desktops to call-center users, letting them work in other locations or even at home without burdening IT support, notes Martin Quigley, senior solutions adviser for adaptive infrastructure at Bell Systems & Technology, which manages Bell Canada’s call centers. “RDP is quite thin,” he notes, so it does not burden the network. But Quigley looks forward to the next release of VMware’s underlying ESX technology, which will support load balancing across servers, making it easier to maintain performance levels as user demands change. (Currently, this is a manual process.)
At Duncan Regional Hospital in Duncan, Okla., the number of desktops more than doubled to about 500 in the past two years. Rather than lobby for money to hire more desktop support techs, CIO Roger Neal decided to deploy ClearCube thin clients and keep the physical management in a central location -- and get more from his existing staff. When ClearCube began supporting VMware virtual machines in 2006, Neal began reconfiguring his blade servers to run three virtual machines per blade, so he wouldn’t need more blades as the demand for desktops increased. He also saw desktop support calls drop by 40 percent, which he attributes to centralized PC management.
Streaming to the desktop
Virtualization at the application host server can make thin clients more efficient to deploy, but many organizations are wedded to having real PCs at users’ disposal despite the support costs. Desktop streaming is emerging as one of the most efficient ways to support this model without incurring the usual bloated desktop support costs.
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Altiris, AppStream, and Microsoft (through its recent acquisition of Softricity) have pushed the concept to the next level, streaming applications rather then a complete desktop environment. This allows greater flexibility in what is provisioned, because IT can create a basic operating system image and then individual images for each application, and combine them as needed on the fly. You don’t need a separate desktop image for each combination of applications.