What is Virtualisation?

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

Virtualisation 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, normalised 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.

Virtualisation 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, Virtualisation was no longer widely employed.

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

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

"In the coming years, virtual machines will move beyond their simple provisioning capabilities and beyond the machine room to provide a fundamental building block for mobility, security and usability on the desktop."

"Virtual machines provide a powerful unifying paradigm for restructuring desktop management."

— Mendel Rosenblum, Chief Scientist, VMware Inc.

Benefits of Virtualisation Partitioning

Multiple applications and operating systems can be supported within a single physical system

Servers can be consolidated into virtual machines on either a scale-up or scale-out architecture

Computing resources are treated as a uniform pool to be allocated to virtual machines in a controlled manner

Isolation

Virtual machines are completely isolated from the host machine and other virtual machines. If a virtual machine crashes, all others are unaffected

Data does not leak across virtual machines and applications can only communicate over configured network connections

Encapsulation

Complete virtual machine environment is saved as a single file; easy to back up, move and copy

Standardized virtualized hardware is presented to the application - guaranteeing compatibility