Virtualization Servers
Concept
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.
Virtualization can be viewed as part of an overall trend in enterprise IT that includes autonomic computing, a scenario in which the IT environment will be able to manage itself based on perceived activity, and utility computing, in which computer processing power is seen as a utility that clients can pay for only as needed. The usual goal of virtualization is to centralize administrative tasks while improving scalability and work loads.
Hardware
* Hardware virtualization, execution of software in an environment separated from the underlying hardware resources
o Hardware-assisted virtualization, where some support for virtualization is built into the underlying hardware
o Full virtualization, sufficiently complete simulation of the underlying hardware to allow software, typically a guest operating system, to run unmodified
o Partial virtualization, where some but not all of the target environment is simulated. Some guests may need modifications to run, see paravirtualization
o Paravirtualization, virtualization environments that require modifications to guest operating systems in exchange for higher efficiency
Memory
* Virtual memory, giving an application program the impression that it has contiguous working memory, isolating it from the underlying physical memory implementation
* Memory virtualization, aggregating RAM resources from networked systems into a single memory pool
Storage
* Storage virtualization, the process of completely abstracting logical storage from physical storage
Software
* Operating system-level virtualization, hosting of multiple virtualized environments within a single OS instance
o Application virtualization, the hosting of individual applications in an environment separated from the underlying OS
* Virtual machine (VM), a software (possibly hardware-assisted) implementation of a computer that executes programs like a real computer
Mobile
* Mobile virtualization, using virtualization technology for mobile phones and other types of connected wireless devices
Data
* Data virtualization, the presentation of data as an abstract layer, independent of underlying database systems, structures and storage
* Database virtualization, the decoupling of the database layer, which lies between the storage and application layers within the application stack
Desktop
* Desktop virtualization, the remote display, hosting or manipulation of a graphical computer environment (desktop)
Network
* Network virtualization, creation of a virtualized network addressing space within or across network subnets
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