What is Virtualisation?

The concept and design goal of virtualisation is to maximize the utilisation, consolidation and flexibility of physical computer resources through the managed sub-division of the physical machine into virtual machines, using software technology. This virtualisation capability is the key enabler of server consolidation.

Utilisation and Consolidation

Historically, maximising the utilisation of the physical computer related to very expensive components like CPUs and memory. As the price of computer hardware has dropped, maximising utilisation, through server consolidation, has now been extended to also include the physical footprint of the computer, its power consumption and the cost of HVAC. Virtualisation and server consolidation not only delivers higher levels of utilisation and cost reduction in these areas, they also drive down the total cost of ownership through reduced on-going system management effort.

Flexibility

Flexibility is achieved through the faster creation, movement and deletion of virtual machines and also the ability to allocate or de-allocate more physical resources to them. This flexibility and speed also contributes to a lower cost of ownership.

Virtualisation isn’t free

Not all applications benefit from operating in a virtualised environment and unfortunately there are no hard and fast rules. While virtualisation delivers utilisation and flexibility benefits, the cost of the extra software layer is performance.

With this in mind there are several factors that need to be taken into account when architecting a system design that incorporates virtualisation.

• Features and capabilities of the virtualisation solution / software selected
• Physical resource levels / constraints on the host physical computer
• Nature of the application – Interactive, batch, real-time, database, etc.
• Resource usage of the application – CPU intensive, I/O intensive, high memory use, etc.
• Time profile of the running application – peak load, when, duration etc.

Velos-IT and Virtualisation