Desktop virtualization (sometimes called client virtualization), as a concept, separates a personal computer desktop environment from a physical machine using a client–server model of computing. The model stores the resulting "virtualized" desktop on a remote central server, instead of on the local storage of a remote client; thus, when users work from their remote desktop client, all of the programs, applications, processes, and data used are kept and run centrally. This scenario allows users to access their desktops on any capable device, such as a traditional personal computer, notebook computer, smartphone, or thin client.
Virtual desktop infrastructure, sometimes referred to as virtual desktop interface (VDI) is the server computing model enabling desktop virtualization, encompassing the hardware and software systems required to support the virtualized environment.
Desktop Virtualization has reached maturity as a solution and is characterized by a server hosting multiple virtual machines, each of which contains an operating system and a set of applications. This operating system and these applications are then served to each user, regardless of the end point device or user location.
- Lower workstation and laptop costs
- Increased data security and improved compliance
- Provide disaster recovery and business continuity for the desktop
- Greater IT operating efficiency through maximum system availability
- Quickly Provision and Manage Desktops and Applications
- Reduce the Costs of Desktop Management
A simple use for desktop virtualization involves remote administration—where the controlling computer will work almost the same as on a duplicate desktop, except that the actions of the controlling computer may be almost unnoticeable on the remote computer display. This differs from simple remote desktop software in that several people can use the same controlling computer at once, without disturbing each others' work. This could be useful for several administrators doing different tasks on the same server. It can also be used for using hardware attached to the controlled computer, without disturbing a person who may already be using the computer.
However, a major use spreads the resources of one machine to several users. In some cases one can buy one large computer (or server) and several thin clients or dumb terminals, rather than purchasing a complete computer for each physical workstation. The controlling thin-client computers need only enough resources to run the remote controlling software, therefore virtualization can provide a very simple and cheap computing system. Users of such a "thin client" or "dumb terminal" may not even know that "their" software actually runs on another computer. If one already has enough computers, but they are not powerful enough, only one new computer may be needed, with the old ones re-usable as thin clients.
The shared resources model inherent in desktop virtualization offers advantages over the traditional model, in which every computer operates as a completely self-contained unit with its own operating system, peripherals, and application programs. Overall hardware expenses may diminish as users can share resources allocated to them on an as-needed basis. Virtualization potentially improves the data integrity of user information because all data can be maintained and backed-up in the data center. Other potential advantages include:
- simpler provisioning of new desktops
- reduced downtime in the event of server or client hardware-failures
- lower cost of deploying new applications
- desktop image-management capabilities
- longer refresh cycle for client desktop infrastructure
- secure remote access to an enterprise desktop environment
Hosted virtual desktops
Hosted virtual desktops result from desktop virtualization services provided through an outsourced, hosted subscription model. Hosted virtual desktop services generally include a managed desktop client operating-system configuration. Security may be physical, through a local storage-area network, or virtual through data-center policies. Transferring information technology infrastructure to an outsourced model can shift accounting for the associated costs from capital expenses to operating expenses.
According to a report by Gartner, hosted services accounted for more than 500,000 desktop units as of March 2009, but will grow to 49 million desktop units by 2013, and may make up as much as 40% of the worldwide "professional PC market" by revenue.