Virtualization

Virtualization has different meanings and applications in terms of its domain depending upon whether it is refered to in computing terms or non-computing environments. In both environments, virtualization opposes transparency, in that something is virtual when it is visible, perceivable, but does not physically exist in the form perceived. Conversely, something is transparent when it exists in the real world, but is not visible in use.

Computing Virtualization

In computing terms, virtualization refers to a technique for hiding the physical characteristics of computing resources from the way in which other systems, applications, or end users interact with those resources.

This enables making a single physical resource [ server, operating system, application, or storage device) appear to function as multiple logical resources.

Alternatively, it can include making multiple physical resources [ storage devices or servers] appear as a single logical resource.

In terms of different asepcts of computing, virtualization has a broad legacy of application, ranging from entire computer systems to individual capabilities or components.

Throughout these different applications, a common element of all virtualization technologies is the hiding of technical detail, through encapsulation.

Virtualization creates an external interface that hides an underlying implementation, for example:

By multiplexing access
By combining resources at different physical locations
By simplifying a control system.

Recent development of new virtualization platforms and technologies has refocused attention on this concept.

In domains abstraction and object orientation, virtualization is used in many different contexts. These can be broadly grouped into two groups:

Platform virtualization - the simulation of virtual machines.
Resource virtualization - the simulation of combined, fragmented, or simplified resources.