Virtualization

Virtualization is the creation of a virtual (rather than actual) version of something, such as an operating system, a server, a storage device or network resources.

the decoupling of a resource or request for a service from the underlying physical delivery of that service such that the consumer needs no knowledge of the characteristics of the delivery system.

A software technology allowing an operating system to run unmodified on an isolated virtual environment, called virtual machine, where a platform's physical characteristics and behaviours are reproduced.

A feature that allows standard users to run applications that normally write to per-computer files and registry keys. If these write operations fail, they are automatically redirected to equivalent per-user locations.

Adding a layer onto some entity so that the new entity exhibits the interface properties of the original. This layer hides the true implementation of the virtualized object so that the original can be changed or replaced without fundamentally impacting the interaction of entities that have a dependency on it. An example is disk LUNs, which present the interface of a disk, yet may be implemented as a whole disk, a partition of a disk or perhaps an aggregation such as a RAID stripe.

Allows interacting with a resource using an abstract mechanism so that the underlying physical resource can be replaced with another one of similar capability without affecting the resource consumer. Virtualization balances supply and demand by providing a transparent, aggregated computing resource.

The pooling of physical storage from multiple network storage devices into what appears to be a single storage device that is managed from a central console

In storage, virtualization is a means by which multiple physical storage devices are viewed as a single logical unit. Virtualization can be accomplished in-band (in the data path) or out-of-band. Out–of–band virtualization does not compete for host resources, and can virtualize storage resources irrespective of whether they are DAS, NAS or SAN.