What is Virtualization?
First, we can start off by defining virtualization; in short “virtualization is abstraction layer,” and it was first introduced in computing during the early 1960s. More clearly with virtualization, the operating system no longer must be bound to the server or the PC that it runs on. The operating system is abstracted from hardware. In other words, the operating system is not installed directly on the hardware, and it is not connected directly to that piece of hardware. There is a layer between the physical server and the operating system which is called virtualization layer. It uses VMware solution for virtualization that would-be VMware ESXi or ESX.
Figure I explains and gives an idea of how the virtualization system is set up. First, there is a physical server on the bottom, and virtualization layer is located above that. Above the virtualization layer, there are little containers; those little blocks are called virtual machines. Those virtual machines are where the operating system is installed, that used to be installed on the physical server. Inside that operating system, the users would install applications.
When we look at Figure I, the virtual machines are running on one physical server. All the different operating systems are inside of that virtual machine and all of those are different virtual computers. All those operating systems are using the same physical computer. This type of virtualization is called server virtualization, and that is the most well-known form of virtualization. With server virtualization, we can install any operating system and make it possible to run them on virtual layer. It is called hypervisor.
The hypervisor allows you to run multiple virtual machines. Each virtualization has its own operating system on the same physical server. There are different brands of hypervisors from different companies (Microsoft, VMware, and Citrix, etc.); those are all virtualization solutions to be installed on the physical server or the virtual host. In figure I, above the physical server, are the virtual machines and each guest operating system is running inside the individual virtual machine.
Hypervisor creates virtualization layer, and it makes server virtualization possible. Hypervisors would be VMware ESX or ESXi, which are part of VMware vSphere. Also, there are some different brand hypervisor, for example, Microsoft Hyper-V, VMware Workstation, XenServer and VMware Fusion which runs on the MAC operating system.