Virtualization : Basic Concepts

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. e.g. hard drive into different partitions, a partition is the logical division of a hard disk drive to create, in effect, two separate hard drives.
Similarly, Operating system virtualization is the use of software to allow a piece of hardware to run multiple operating system images at the same time.

There are three areas of IT where virtualization is making head roads
a) Network virtualization
b) Storage virtualization
c) Server virtualization

Today, virtualization is in the forefront - helping businesses with scalability, security and management of their global IT infrastructure.

Virtualization can host multiple guest operating systems. Each guest operating system runs in its own domain, Virtualization schedules virtual CPUs within the virtual machines to make the best use of the available physical CPUs. Each guest operating systems handles its own applications. These guest operating systems schedule each application accordingly.

You can deploy Virtualization in one of two choices: full virtualization or Para virtualization.

Full virtualization provides total abstraction of the underlying physical system and creates a new virtual system in which the guest operating systems can run. No modifications are needed in the guest OS or application (the guest OS or application is not aware of the virtualized environment and runs normally).

Para virtualization requires user modification of the guest operating systems that run on the virtual machines (these guest operating systems are aware that they are running on a virtual machine) and provide near-native performance.

To know more on Virtualization:
Intro to Virtualization,
SearchServerVirtualization.com,
Red Hat Enterprise Linux Virtualization.