Virtualization

Virtualization is an abstraction layer that decouples  physical hardware from the operating system to deliver greater IT resource utilization and flexibility.

Virtualization allows multiple virtual machines, with heterogeneous operating systems to run in isolation, side-by-side on the same physical machine. Each virtual machine has its own set of virtual hardware (e.g., RAM, CPU, NIC, etc.) upon which an operating system and applications are loaded. The operating system sees a consistent, normalized set of hardware regardless of the actual physical hardware components.

Virtual machines are encapsulated into files, making it possible to rapidly save, copy and provision a virtual machine. Full systems (fully configured applications, operating systems, BIOS and virtual hardware) can be moved, within seconds, from one physical server to another for zero-downtime maintenance and continuous workload consolidation.

Virtualization was first introduced in the 1960s to allow partitioning of large, mainframe hardware -a scarce and expensive resource. Over time, minicomputers and PCs provided a more efficient, affordable way to distribute processing power, so by the 1980s, virtualization was no longer widely employed.

In the 1990s, researchers began to see how virtualization could solve some of the problems associated with the proliferation of less expensive hardware, including underutilization, escalating management costs and vulnerability.