WHAT IS VIRTUALISATION?
Virtualisation is a software technology that
divides a physical resource, such as a server, into
virtual resources called virtual machines (VMs)
(see figure 1). Virtualisation helps to consolidate
physical resources, simplify deployment and
administration, and reduce power and cooling
requirements.
Virtualisation in a computing system adds
a layer of abstraction between two layers in
that computer system. The layer of abstraction
is a software layer between the hardware and the guest operating systems. The layer acts as
a resource manager to enable the sharing of
processing power and memory. This software
is called a virtual machine monitor (VMM) or
hypervisor. VMMs virtualise the hardware of a
physical machine and partition it into multiple,
logically separated VMs. The VMM monitors
everything that happens inside a VM, and it
enforces resource management policies on the
VM. Multiple operating systems (OSs) can
coexist on the same virtual machine in isolation
from one another and can operate simultaneously
on a single server. Virtualisation allows
companies to eliminate dedicated hardware-based
servers—saving acquisition, maintenance and
electricity costs.