1. Virtualisation Overview
Virtualisation is a technology set that allows for the abstraction of ICT services from the underlying
hardware platforms. The most popular implementation of virtualisation (after network virtualisation)
is that of Server Virtualisation.
Driven primarily by the desire to maximize the efficiency of server/data centre estates, server
virtualisation allows organisations to increase the efficiency of physical server platforms. Typically,
server virtualisation achieves at least a 30% reduction in physical servers and drives server
performance efficiency up from an average of 30% usage to over 80% usage. Coupled with this is
the ability to quickly provision new services on existing physical platforms, brings speed and agility
to what was once an elongated procurement cycle before new services were brought on-line.
Simply put, virtualisation is a means by which to make more efficient use of either existing
computing capacity or consolidate services on to new hardware platforms.
This is better explained by the following example:
 An x86 server running virtualisation software can host virtual machines running, for
instance, Linux or Mac OSX. The physical x86 server would be the host machine and the
virtual machines are guest machines.
 Under this scenario, it would be possible to run an Exchange Server on Windows, Apache
web server on centos and a File server all on the same machine.
 This approach allows the host hardware to work at nearer 90% capability.
There are a number of types and applications of virtualisation:
 Hardware virtualisation or platform virtualisation. The above case is an example of this;
one item of hardware is used to emulate several - this can also be known as hardware
emulation.
 Network virtualisation provides the ability to abstract logical networks from the underlying
hardware, allowing for the creation of virtual networks, which span physical devices and
boundaries.
 Storage Virtualisation is the pooling of physical storage from multiple network storage
devices into what appears to be a single storage device that is managed from a central
console.
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2.  Application virtualisation provides a mechanism to distribute applications to desktop
machines, and for software to run in non-native environments, e.g. running a Windows app
in a Linux environment. The application is tricked into thinking it is in a native OS.
 Data virtualisation presents data as an abstracted layer separate from the underlying
systems and storage structures, allowing access to multiple data sources from a single
access point.
 Desktop Virtualisation - Desktop Virtualisation is the detachment of the desktop, the
operating system and the end-user applications from the underlying endpoint or device.
This enables standard thin-client end user device, tablets and other devices to access a
centrally hosted desktop environment.
Business benefits of Virtualisation
 Saves money on hardware costs, as more services can be provided with less physical
hardware.
 Environmentally sound. Server virtualisation consumes less power, whilst less heat is
emitted and fewer resources are needed overall.
 Saves physical rack-space and the energy involved in cooling the servers.
 Increases the efficiency of administration, as automation and self-service tools can be
deployed.
 Deployment cost and time is reduced. There is no need to install new hardware or network
connectivity - it is simply a case of adding a new virtual server or application, which can
take minutes.
 Hardware utilisation is increased from around 15-30% to 80-90%.
 Back up and redundancy can be significantly more affordable. Often existing servers can
be used following a virtualisation roll out.
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3. Considerations
With virtualisation comes complexity, and without a robust management framework and
automation process in place, many virtualised server estates either stall, or sprawl, replicating in
the virtual environment what occurred in the physical environment. This can often result in
increased physical estate and an inefficient virtual environment.
Managing complexity at this layer can be challenging. The focus must be on automating for
efficiency, managing to ensure the infrastructure meets the needs of the business and securing
and protecting critical resources.
Moving to virtualisation can be perceived as challenging, particularly if:
 Organisations do not have the skills in-house to deploy virtualisation
 Organisations do not have the tools to deploy and manage virtualisations
 Network managers are wary of the complexity of virtual machines
 Application owners have concerns about virtual performance.
Server virtualisation should be approach in the same way as any other IT project, with a clear
definition of the objectives, an evaluation as to what virtualisation elements the organisation will
see benefit from, and with clear roll out plans in place.
Virtualisation Glossary
 “Bare Metal” installation: Where the virtualisation software is installed directly to the
hardware rather than on an operating system.
 P2V (Physical to Virtual): The process of migrating from a physical environment to virtual.
 Hypervisor: The software or layer that allows you to create a virtual installation on the host
hardware.
 VM: Virtual Machine
 Snapshot: An image of the state of a virtual machine at a specific point in time. A
snapshot includes all the data and configuration information for the VM, which allows the
machine to be rolled back to that previous state after making changes.
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