- In virtualization, a single physical instance of an application or resource is shared among multiple organization or tenants (customers).
- It does so by assigning a logical name to physical resources and providing a pointer to that physical resource when demanded
- Creating a virtual machine over existing operating system and hardware is referred as Hardware Virtualization.
- Virtual Machines provide an environment that is logically separated from the underlying hardware.
- The machine on which the virtual machine is created is known as host machine and the virtual machine is referred as a guest machine.
- This virtual machine is managed by a software or firmware, which is known as a hypervisor.
The hypervisor is a firmware or low-level program that acts as a Virtual Machine Manager. There are two types of hypervisor:
Type 1 hypervisor runs on the bare system. LynxSecure, RTS Hypervisor, Oracle VM, Sun xVM Server, VirtualLogic VLX are examples of Type 1 hypervisor.
Note: The type1 hypervisor does not have any host operating system because they are installed on a bare system.
Type 2 hypervisor is a software interface that emulates the devices with which a system normally interacts. Containers, KVM, Microsoft Hyper V, VMWare Fusion, Virtual Server 2005 R2, Windows Virtual PC and VMWare workstation 6.0 are examples of Type 2 hypervisor.
Type of Hardware Virtualization
There are mainly three types of hardware virtualization:
1. Full Virtualization
2. Emulation Virtualization
3. Para virtualization
Full Virtualization: Here, the underlying hardware is completely simulated. Guest software does not require any modification to run
Emulation Virtualization: In Emulation, the virtual machine simulates the hardware and hence became independent of it. In this, the guest operating system does not require modification.
Para virtualization: In Para virtualization, the hardware is not simulated. The guest software run their own isolated domains
Note: VMware vSphere is highly developed infrastructure that offers a management infrastructure framework for virtualization. It virtualizes the system, storage, and networking hardware