Virtual Machine Operating System Computer Science Essay

Published Date: 02 Nov 2017

V.Mounisha,CSE,SNIST

[email protected],8985287889

T.Vyshnavisrilaxmi,IT,SNIST

[email protected],8500599958

Abstract -

Virtualization enables installation and running of multiple virtual machines on the same computer system.There are many types of Virtualization.For Operating System Virtualization, Operating system that communicates directly with hardware is known as the host operating system whereas virtual operating systems have all the features of a real operating system, but they run inside the host operating system.Hardware virtualization or platform virtualization refers to the creation of a virtual machine that acts like a real computer with an operating system. For example,Windows XP, Windows Vista and Windows 7 are used as host operating systems using Windows Vista as a virtual operating system. Highlevel Language Virtualization generally includes Java virtual machine etc.,

Keywords-Virtualization,Virtual machine,Operating System,Virtual computer,Host computer.

INTRODUCTION

The virtual machine is a technology that creates one or multiple virtual environments on a single physical machine. The virtual machines are isolated from each other and the underlying physical machine, and they give users the illusion of accessing a real machine directly. The virtual machine is a completely independent computer system and a virtual operating system needs regular updates and antivirus protection and it also has its own IP address. Virtual machines have been widely used in the following applications:

Server consolidation,

Intrusion and fault tolerance,

System migration,

Virtual appliance,

Debugging and testing.

There are many ways how to provide the virtualized environment. Virtualization layer generally maps

virtual requests from a virtual machine to physical requests.In performance evaluation, The tools compared are native OS,Microsoft Virtual PC, VMware server on Windows and Linux host OS.Generally we use Microsoft Virtual PC because our host and virtual operating systems are of Microsoft. Virtual PC is based on the VMM (Virtual Machine Monitor) and it allows running of multiple operating systems at the same time on a single computer system.

Virtual PC emulates all components of a standard 32-bit based personal computer except the CPU.For operating system Virtualization,Window7 acts as the best host operating system. Windows operating systems are most widely used operating systems on desktop and portable computers.

VIRTUALIZATION

Increased development of modern technologies makes the user to face software incompatability.Earlier applications that are important for the user do not work on new software. Hence,the best solution for this is virtualization. Virtualization is a technique for hiding the physical characteristics of computing resources from the way in which other systems, applications or end users interact with those resources. Generally, virtualization occur at three levels:

1.Operating System level Virtualization

2.Hardware Level Virtualization

3.High level language Virtualization

Operating System level Virtualization:

It is a method that allows installation of other operating systems inside the existing one. The operating system existing on a certain computer system is called a host operating system and a new installed operating system is called virtual. The tool used for installing virtual operating systems creates a virtual computer and a virtual operating system is installed on a virtual computer so it is not directly connected to hardware resources. This virtual computer in combination with the virtual operating system is called a virtual machine.

Hardware level Virtualization:

A virtual computer emulates the older hardware resources with lower performance than the actual ones.

A virtual machine manages hardware resources through the host operating system. Virtual machine runs on the identical hardware, but on different host operating systems.

High level Language Virtualization:

This Virtualization layer creates an application.Programs written on this virtual machine can run regardless of the host operating systems.

Example:

Consider an example for Virtualization in Operating Systems.Windows operating systems are most widely used operating systems, so we can use three latest versions of Windows as the host operating systems: Windows XP Professional ,Windows Vista and Windows 7 Professional. Microsoft Virtual PC 2007 is used as a tool for virtualization and Windows Vista is used as a virtual operating system. Performance measurement and evaluation is done in the same controlled conditions for all three host operating systems with different benchmark applications. These benchmark applications are used for measuring virtual machine performance and they measure various values. Performance evaluation is done by comparing virtual machine performance measurement results when it is installed on three different host operating systems.

TYPES OF VIRTUALIZATION

There are many types of virtualization,namely

Hardware Virtualization

Desktop Virtualization

Software Virtualization

Memory Virtualization

Storage Virtualization

Data Virtualization

Network Virtualization

A.Hardware Virtualization:

Hardware Virtualization refers to creation of a virtual machine in our actual system.Software working on this virtual machine is separated from the actual hardware. A computer running through Microsoft Windows  may host a virtual machine that looks like a computer with the Ubuntu Linux operating system.Host machine is the actual machine and the virtual machine is which we installed as vitual OS. The software that creates a virtual machine on the host hardware is called a Hypervisor.

Types of Hardware Virtualization:

A)Full Virtualization:Complete simulation of the actual hardware to allow software, which typically consists of a guest operating system, which is unmodified.

B)Partial Virtualization: Some but not all of the target environment is simulated. Some guest programs, therefore, may need modifications to run in this virtual environment.

C)ParaVirtualization: A hardware environment is not simulated; but the guest programs are executed in their own isolated domains, as if they are running on a separate system. Guest programs need to be specifically modified to run in this environment.

Hardware-assisted virtualization is a way of improving the efficiency of hardware virtualization. It involves employing specially designed CPUs and hardware components that help improve the performance of a guest environment.

B.Desktop Virtualization:

Through Desktop Virtualization,we can separate the logical desktop from the physical machine.

 Virtual desktop infrastructure (VDI),is 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.Large companies generally move workloads from PCs and other devices to data centers, creating virtual clients, with applications and client operating environments hosted on servers and storage in the data center. This type of Virtualization is very much used here.

Other types-

C.Software:

Hosting of multiple virtualized environments in a single OS.This type of Virtualization is generally used by many people for installing a virtual OS into their systems.

D.Memory:

Memory virtualization, aggregates random-access memory (RAM) resources from networked systems in as a single memory.

E.Storage:

Storage virtualization is the process of completely abstracting logical storage from physical storage.

F.Data:

Data virtualization, the presentation of data as an abstract layer, independent of underlying database systems, structures and storage.

G.Network:

Netwok Virtualization creation of a virtualized network addressing space within or across network subnets.

SETUP OF A VIRTUAL MACHINE

For the host system, a virtual machine is just another running application that requests hardware

resources. Performance of a virtual machine depends on host operating system resource management. A host

operating system that has more efficient hardware and software resources allocation will provide better

performance for running a virtual machine. Hardware components with the greatest influence on the performance

are as follows:

Memory – memory size of a virtual computer can take at most half the size of system memory.

CPU – as Virtual PC does not emulate the CPU, a virtual machine executes a certain instruction directly on system CPU.

Graphics subsystem – as an emulated graphics subsystem has only 8 MB of memory, we could not run new graphics benchmark applications.

Hard disk drive – a virtual machine uses hard disk drive resources by creating virtual disk partition.

METHODOLOGY

To avoid errors during performance measurements and to ensure the same conditions for all operating systems, in every operating system the following steps were performed:

1. Install the host operating system,

2. Install the latest device drivers and operating system updates,

3. Install Microsoft Virtual PC 2007,

4. Set a virtual machine with 1 GB of memory and 40 GB of virtual hard disk,

5. Install a virtual operating system (Windows Vista Business SP2),

6. Install the latest device drivers and operating system updates for a virtual operating system,

7. Turn off network, screen saver, system restore and user account control (only for Windows Vista and

Windows 7),

8. Install the benchmark application,

9. Reboot computer system three times,

10. Run Virtual PC,

11. Run the benchmark application,

12. Uninstall the benchmark application.

ADVANTAGES

The main advantages of virtualization in general are as follows:

1.It can rapidly reduce cost and dangerousness of the experiments

2. Portability of a virtual machine to another is simple

3.It has improved security

4. It enables parallelization,

5.It decreases time expenses needed for administration of a large amount of desktops and workstations, etc.

DISADVANTAGES

1.It needs more resources

2.Degraded Performance

3.Application Virtualization is always not possible.

CONCLUSION

The concept of virtualization is very broad and can be applied to devices, servers, operating systems, applications and even networks.Now a days Virtualization is also having a large impact on Education in the institutes like IBM and also in the tourism industry in countries like Taiwan.