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.
" 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.
"
— Mendel Rosenblum, Chief Scientist, VMware
Inc.
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.
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 standardised virtualised hardware is presented to
the application - guaranteeing compatibility.