02-05-2013, 03:10 PM
Virtualization
Virtualization.pptx (Size: 315.84 KB / Downloads: 16)
Invention
Virtual machine concept was in existence since 1960s when it was first developed by IBM to provide concurrent, interactive access to a mainframe computer.
IBM developed virtualization at Cambridge Scientific Center.
After a long period of research IBM released the CP/CMS operating system in the early 1970’s as the first to be commercially available with built in virtualization functionality.
What is Virtualization?
”Virtualization is a technology that combines or divides computing resources to present one or many operating environments using methodologies like hardware and software partitioning or aggregation, partial or complete machine simulation, emulation, time-sharing, and many others”.
Hardware virtualization
A computer that is running Microsoft Windows may host a virtual machine that looks like a computer with the Ubuntu Linux operating system; Ubuntu-based software can be run on the virtual machine.
In hardware virtualization, the host machine is the actual machine on which the virtualization takes place, and the guest machine is the virtual machine.
Hypervisor
The software or firmware that creates a virtual machine on the host hardware is called a HYPERVISOR or Virtual Machine Manager. A hypervisor (a piece of software) imitates a particular piece of computer hardware or the entire computer.
Definition
“A hypervisor (also: virtual machine monitor) is a virtualization platform that allows multiple operating systems to run on a host computer at the same time.”
Hypervisors are currently classified in two types:
Type 1 hypervisor is software that runs directly on a given hardware platform (as an operating system control program). A "guest" operating system thus runs at the second level above the hardware.
Advanced Capabilities
Snapshotting:- A snapshot is the state of a virtual machine, and, generally, its storage devices, at an exact point in time.
Teleportation:- The snapshots described above can be moved to another host machine with its own hypervisor; when the VM is temporarily stopped, snapshotted, moved, and then resumed on the new host, this is known as teleportation.
Failover.
Cons
1) Security risks may appear due to new unproven abstraction layer.
2) There may be large, single point of failure which may result in loss of whole data due to consolidation of server and storage virtualization.