What is desktop virtualization?
As with other uses of the term “virtualization”, desktop virtualization could really mean the use of several different virtualization technologies (see the Kusnetzky Group model of virtualization to the left) including the following:
- Access virtualization - Individuals access applications running in virtual machines on servers or blade PCs that are located in the datacenter. Sometimes this access virtualization technology is known as “presentation services.” Individuals use a PC running special software, a very lightly configured, limited function computing device known as a “thin client”, a tablet running special software or a smartphone running special software to access their applications and data. Benefits of this approach include greater levels of security and reliability; lower costs of client administration and, in the case of thin clients, the device can be seen as an information appliance rather than a computer. A network connection, however, is required to make this approach work and so, highly mobile staff members would not be able to use this as their primary means of using application solutions.
- Application virtualization - Another approach to desktop virtualization is for individuals to access applications that have been encapsulated and streamed, in whole or in part, down to their local computing device. Once the individual has completed the task, the application could be automatically removed from the local machine and made available for reuse on another machine or it could remain on the local machine. Streaming applications often require broadband network connections. Not all applications work well in an encapsulated form. This also usually means that the target machine is running the operating system and provides a computing environment that streamed applications find hospitable. While it is possible to project a Windows application in a form that can run on a Windows laptop computer or PC, it may not be possible to run a Windows application on an Apple iPad since the operating systems and microprocessor are not the same in both environments.
- Processing virtualization – Processing virtualization is a range of technologies that allow a single computer to appear as many (virtual machine software) or many computers to appear as a single computing environment (clusters, grids, and the like). If we limit the discussion to virtual machine software, one of the five different forms of processing virtualization technologies, a whole computing environment can be encapsulated into a virtual machine. The virtual machine could then be run on a remote server or migrated to the client machine from shared network storage, copied or streamed to the target machine and then executed on the target machine. The target machine need not run the same operating system that supports the application. This approach is the foundation of independent computing. NComputing has focused on a different processing virtualization technology, operating system virtualization and partitioning. (see Converation with NComputing - putting VMs and VDI in its place for a longer discussion on operating system virtualization.)