Virtualization Types In Cloud Computing Pdf Download

Virtualization types in cloud computing pdf download

What Are The Benefits Of Virtualization?

In computing, virtualization refers to the act of creating a virtual rather than actual version of something, including virtual computer hardware platforms, storage devices , and computer network resources. Virtualization began in the s, as a method of logically dividing the system resources provided by mainframe computers between different applications. Since then, the meaning of the term has broadened.

Hardware virtualization or platform virtualization refers to the creation of a virtual machine that acts like a real computer with an operating system.

Software executed on these virtual machines is separated from the underlying hardware resources. For example, 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.

Virtualization types in cloud computing pdf download

In hardware virtualization, the host machine is the machine which is used by the virtualization and the guest machine is the virtual machine. The words host and guest are used to distinguish the software that runs on the physical machine from the software that runs on the virtual machine.

Virtualization types in cloud computing pdf download

The software or firmware that creates a virtual machine on the host hardware is called a hypervisor or virtual machine monitor. Hardware-assisted virtualization is a way of improving overall efficiency of virtualization. It involves CPUs that provide support for virtualization in hardware, and other hardware components that help improve the performance of a guest environment.

Hardware virtualization can be viewed as part of an overall trend in enterprise IT that includes autonomic computing , a scenario in which the IT environment will be able to manage itself based on perceived activity, and utility computing , in which computer processing power is seen as a utility that clients can pay for only as needed. The usual goal of virtualization is to centralize administrative tasks while improving scalability and overall hardware-resource utilization.

With virtualization, several operating systems can be run in parallel on a single central processing unit CPU. This parallelism tends to reduce overhead costs and differs from multitasking, which involves running several programs on the same OS.


Using virtualization, an enterprise can better manage updates and rapid changes to the operating system and applications without disrupting the user. Hardware virtualization is not the same as hardware emulation. In hardware emulation, a piece of hardware imitates another, while in hardware virtualization, a hypervisor a piece of software imitates a particular piece of computer hardware or the entire computer.

Furthermore, a hypervisor is not the same as an emulator ; both are computer programs that imitate hardware, but their domain of use in language differs. A snapshot is a state of a virtual machine, and generally its storage devices, at an exact point in time. A snapshot enables the virtual machine's state at the time of the snapshot to be restored later, effectively undoing any changes that occurred afterwards.

This capability is useful as a backup technique, for example, prior to performing a risky operation. Virtual machines frequently use virtual disks for their storage; in a very simple example, a gigabyte hard disk drive is simulated with a gigabyte flat file.

Any requests by the VM for a location on its physical disk are transparently translated into an operation on the corresponding file. Once such a translation layer is present, however, it is possible to intercept the operations and send them to different files, depending on various criteria.


Every time a snapshot is taken, a new file is created, and used as an overlay for its predecessors. New data is written to the topmost overlay; reading existing data, however, needs the overlay hierarchy to be scanned, resulting in accessing the most recent version. Thus, the entire stack of snapshots is virtually a single coherent disk; in that sense, creating snapshots works similarly to the incremental backup technique. Other components of a virtual machine can also be included in a snapshot, such as the contents of its random-access memory RAM , BIOS settings, or its configuration settings.

Restoring a snapshot consists of discarding or disregarding all overlay layers that are added after that snapshot, and directing all new changes to a new overlay.

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 migration. If the older snapshots are kept in sync regularly, this operation can be quite fast, and allow the VM to provide uninterrupted service while its prior physical host is, for example, taken down for physical maintenance. Similar to the migration mechanism described above, failover allows the VM to continue operations if the host fails.

Generally it occurs if the migration has stop working. However, in this case, the VM continues operation from the last-known coherent state, rather than the current state, based on whatever materials the backup server was last provided with. A video game console emulator is a program that allows a personal computer or video game console to emulate a different video game console's behavior.

Video game console emulators and hypervisors both perform hardware virtualization; words like "virtualization", "virtual machine", "host" and "guest" are not used in conjunction with console emulators.

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Nested virtualization refers to the ability of running a virtual machine within another, having this general concept extendable to an arbitrary depth. In other words, nested virtualization refers to running one or more hypervisors inside another hypervisor.

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Nature of a nested guest virtual machine does not need not be homogeneous with its host virtual machine; for example, application virtualization can be deployed within a virtual machine created by using hardware virtualization. Nested virtualization becomes more necessary as widespread operating systems gain built-in hypervisor functionality, which in a virtualized environment can be used only if the surrounding hypervisor supports nested virtualization; for example, Windows 7 is capable of running Windows XP applications inside a built-in virtual machine.

Furthermore, moving already existing virtualized environments into a cloud, following the Infrastructure as a Service IaaS approach, is much more complicated if the destination IaaS platform does not support nested virtualization.

Virtualization types in cloud computing pdf download

The way nested virtualization can be implemented on a particular computer architecture depends on supported hardware-assisted virtualization capabilities. If a particular architecture does not provide hardware support required for nested virtualization, various software techniques are employed to enable it.

Virtual machines running proprietary operating systems require licensing, regardless of the host machine's operating system. For example, installing Microsoft Windows into a VM guest requires its licensing requirements to be satisfied.

Virtualization Explained

Desktop virtualization is the concept of separating the logical desktop from the physical machine. One form of desktop virtualization, virtual desktop infrastructure VDI , can be thought of as a more advanced form of hardware virtualization. Rather than interacting with a host computer directly via a keyboard, mouse, and monitor, the user interacts with the host computer using another desktop computer or a mobile device by means of a network connection, such as a LAN , Wireless LAN or even the Internet.

In addition, the host computer in this scenario becomes a server computer capable of hosting multiple virtual machines at the same time for multiple users.

What is Virtualization?

As organizations continue to virtualize and converge their data center environment, client architectures also continue to evolve in order to take advantage of the predictability, continuity, and quality of service delivered by their converged infrastructure. For example, companies like HP and IBM provide a hybrid VDI model with a range of virtualization software and delivery models to improve upon the limitations of distributed client computing.

For users, this means they can access their desktop from any location, without being tied to a single client device. Since the resources are centralized, users moving between work locations can still access the same client environment with their applications and data.

Another form, session virtualization, allows multiple users to connect and log into a shared but powerful computer over the network and use it simultaneously. Each is given a desktop and a personal folder in which they store their files.

It also enables centralized control over what applications the user is allowed to have access to on the workstation.

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Moving virtualized desktops into the cloud creates hosted virtual desktops HVDs , in which the desktop images are centrally managed and maintained by a specialist hosting firm. Benefits include scalability and the reduction of capital expenditure, which is replaced by a monthly operational cost. Operating-system-level virtualization, also known as containerization, refers to an operating system feature in which the kernel allows the existence of multiple isolated user-space instances.

Such instances, called containers, [17] partitions, virtual environments VEs or jails FreeBSD jail or chroot jail , may look like real computers from the point of view of programs running in them.

A computer program running on an ordinary operating system can see all resources connected devices, files and folders, network shares , CPU power, quantifiable hardware capabilities of that computer. However, programs running inside a container can only see the container's contents and devices assigned to the container.

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Containerization started gaining prominence in , with the introduction of Docker. From Wikipedia, the free encyclopedia. Act of creating a virtual version of something. Main article: Hardware virtualization.

Related terms:

See also: Mobile virtualization. Main article: Snapshot computer storage. Main article: Migration virtualization. Main article: Failover. Main article: Video game console emulator. Main article: Desktop virtualization.

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Main article: Operating-system-level virtualization. Retrieved Electronic Commerce A Managerial Perspective. October Retrieved 6 July A virtual computer is a logical representation of a computer in software.

By decoupling the physical hardware from the operating system, virtualization provides more operational flexibility and increases the utilization rate of the underlying physical hardware. KVM forum. CBS Interactive. Finn explained that Standard covers 2 CPUs in a host, and goes from one VOSE virtual operating system environment - 1 free Std install in a VM on that host to two, and 'now has all the features and scalability of Datacenter.


Retrieved 5 July Retrieved 22 December Microsoft Corporation. April Retrieved 22 July Archived from the original on January 13, Retrieved December 2, Intrinsic Technology. Archived from the original PDF on 2 October Retrieved 30 August Network World.

Network World, Inc. Archived from the original PDF on March 30, Retrieved July 18, Virtualization software.

Virtualization types in cloud computing pdf download

Comparison of platform virtualization software.