What is Virtualization?

Virtualization means creating virtual form of hardware and/or software resources. Virtualization of server means partitioning physical server into several virtual servers, or machines. In which each virtual machines are isolated, so it can interact with other devices, applications, user and data independently. So it helps to install/run different operating systems in virtual machines although it runs under same physical server. Since it has the isolation feature, if one virtual machine crashes it will not affect the another virtual machine.

 Virtualization is not only about partitioning resources, it can also combine group of physical server into single server. Main concept of virtualization is utilizing the resource usefully by either partitioning or combining.

Why virtualization?

Take an example of data center, most of the machines utilize only 10-15% of its total capacity most of the time which results in wastage of electricity and maintenance cost.To make the optimal utilisation of the remaining capacities we can use Virtualization concepts which also helps to avoid installation of platform/application specific data centers.

How virtualization can be done? Who will take care of isolation of virtual machine (or) server?

Hypervisor is also known as a virtualization manager, which adds a new layer between the hardware and the operating system (see above picture). Hypervisor software separates the operating system and applications from the hardware resources. And it also controls the amount of access that each virtual machine have with hardware resources, such as processor, memory and disk input/output.

What are all the types of virtualization?

Nowadays lot of new types are evolving in virtualization field, we see few of its types

Storage virtualization -  Multiple storage resources in a network are combined into a single storage device for centralized access.

Network virtualization – Network bandwidth is split into independent channels and assigned to a particular server or device.

Application virtualization – Application can be separated from operating system for relocating.

Desktop virtualization – It is similar to server virtualization, but we create number of virtual machines which user can access remotely and use like personal computer. It helps in easy upgradation and maintenance of all desktops

Example: Consider Server with 8GB memory, 1TB storage and 20 core processor. Using virtualization this resources can be split in 8, 10, even 20 virtual machine. There is no condition like each virtual machine which come under one server should have equal amount resources. One virtual machine can have 1GB memory, 100GB storage and 2 core processor, whereas the other one can have 4GB memory, 200GB storage and 5 core processor, depending on the requirement.

List of Vendors offering virtualization software:

ü VMWare

ü Citrix

ü Microsoft Hyper-V

ü IBM PowerVM

ü RedHat Xen

ü Oracle VM Manager, etc.

We will see, what relation between virtualization and cloud computing in upcoming post.