Server virtualisation refers to splitting up the physical server into many virtualised private servers by means of a software called hypervisors. Each virtualised server works independently of others having their own operating system and resources. VPS Hosting utilises this concept to provide users with virtual servers having allocated resources.
Types of Server Virtualisation
There are three approaches to server virtualisation, and is based on the level of virtualisation each provides:
- Machine level virtualisation: Also known as full virtualisation, as it gives the utmost isolation. Each virtual environment runs its own operating system and as an autonomous server. It utilises the host-guest paradigm, where the guest is unaware of the host operating system. However, a hypervisor is used as the management layer between the guest and the host to direct instructions to the CPU.
- Paravirtual machine: This model involves porting, which is a modification of the guest’s operating system by the hypervisor. It is better suited for scenarios which require multiple virtual machines. Popular examples of software which uses paravirtual machines include Xen and UML.
- OS level virtualisation: In this model, the host and the guests use the same operating system. However, different versions of the same operating system can be installed. Examples of OS layer virtualisation are Virtuozzo and Solaris Zones.
Advantages of server virtualisation:
- Reduced expenditure: Server virtualisation not only help in saving on capital expenditure but also reduces operational expenditure. Since the hardware size is reduced, there is lower energy consumption which adds in lower overall cost. This