A Virtual machine is a software application to be run in its own operating system. It is not physically exist to execute it’s a program or operating system which should be create an another environment. It is an isolated duplicate of real machine. It should be exactly act like a normal computer and carries its own virtual i.e. software based. A virtual machine is a guest and runs inside in its operating system are called a host. It’s produced to execute an instruction set unlike of host environment. A multiple virtual machines are executed by a single host environment because of they are differ from the physical resources.
Fig1:- virtual machine
Virtual machines are categorized into two major categories according to their use of any real machine. A system virtual machine and a process virtual machine. A system virtual machine which bears the complete system platform of a complete operating system. The main purpose to design a process virtual machine is to execute the single program in the single processor. Virtual machine is act like a virtual software and virtual hardware we can run the applications same as like an physical computer and we can use the virtual hardware same as like an physical hardware components exist, also virtual machines offered a lot of advantages while compared to general physical machine.
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2.1 SYSTEM VIRTUAL MACHINE
System virtual machine is as well addressed as hardware virtual machine is leave the sharing of real machine resources between virtual machines in physical computer a virtual machine is executed by its own operating system. a virtual machine monitor is run on top of an operating system, a virtual machine monitor is a virtualization provided by an software layer.
Fig 2:- SYSTEM VIRTUAL MACHINE
The advantages of virtual machines are:
Multiple operating systems are existing in the same computer and strong isolation environment is there in between them.
A virtual machine is also a software which executed by a set of instructions that is somewhat different from a physical machine.
Maintenance, disaster recovery and high availability compared to real machine.
Disadvantages of virtual machines are:
A virtual machine approaches the hardware indirectly so it’s a less efficient.
At the same time a multiple virtual machines are executing on the same host to get a chance of unstable performance like speed of execution, its depends on work load of other virtual machine to recover that a proper techniques are used.
Multiple virtual machines are running in the same physical machine called guest operating system. In that real machine often used in server consolidation, different services are executed on individual virtual machines in order to avoid interference.
The main motivation of the virtual machine is to run multiple operating systems, in a single physical machine and which allowed for time sharing in between the operating systems, different tasks handled by operating systems. At the introduction stage virtual memory is one of the general considerations of system virtual machine. the single-user operating system of each user providing time sharing and full virtual machine of the first system implemented by IBM’s CP/CMS.
The same operating systems does not use the same guest operating systems, making to run different operating systems on the same computer like Microsoft windows and Linux, or more previous versions of an operating system. The main purpose of the virtual machine is to run dissimilar operating systems in the same machine and becoming popular in embedded systems it is to be use of real time operating systems and also an high level operating systems such as Linux or windows.
2.2 Process virtual machines
A process virtual machine also described as application virtual machine, it executes only a normal application inside an operating system it holds only a single process this virtual machine is started is when the process is started or destructed once it exists. System virtual machine and process virtual machine has different features this process virtual machine main purpose is to allow a platform independent program environment that lifts the details of operating system or hardware.
Diagram of the P2V online conversion process.
Fig 3:- process virtual machine
Process virtual machine allows a high level programming language these virtual machines are implemented using an interpreter according to the performance of compiled programming languages is attained by the function of just-in-time compilation. Such as virtual machine is also more popular in java programming language which implemented by java virtual machine and also other language of .NET Framework, which runs on VM of common language run time.
In the special case of process virtual machines are over the communication mechanisms of a group of linked computers, this virtual machines does not support single process. Only it executes a single process per physical machine in that group. These tasks are easily designed for programming parallel applications by allowing the programmer focus on algorithms instead of communication mechanism allowed for interconnect and the OS.
2.3 List of Hardware supported for virtual machine
Alcatel-Lucent 3B20D/3B21D simulated on commercial off-the-shelf computers with 3B2OE or 3B21E system.
AMD-V (formerly code-named Pacifica)
ARM Trust Zone
Free scale PowerPC MPC8572 and MPC8641D
Intel VT-x (formerly code-named Vander pool)
IBM System/370, System/390, and zSeries mainframes
HP vPAR and cell based nPAR
GE Project MAC
Honeywell Multics systems
IBM Systems/360 Model 145 Hardware emulator as Honeywell 200/2000 systems
Xerox Sigma 6 CPUs were changed to emulate GE per Honeywell 600/6000 systems
Honeywell Level 6 mini computers emulate by predecessor 316/516/716 minis
List of virtual machine software:
2.4.1 System (Hardware) virtual machine software
ATL (A MTL Virtual Machine)
Bochs, mini open source x86 and AMD64 PCs emulator
Co Linux Open Source Linux within Windows
CoWare Virtual Platform
Lynx Secure employs the MILS architecture to allow high authority for embedded systems on x86
Windows Virtual PC (formerly Microsoft Virtual PC) and Microsoft Virtual Server
QEMU, is a simulator based on the virtual machine.
Sun x VM
two OS two
Virtual Iron (Virtual Iron 3.1)
VM from IBM
VMware (Virtual Server ,ESX Server, Fusion, ACE , Workstation, Player and)
2.4.2 Process (Application) virtual machine software:
Baan Bshell Virtual Machine – Baan 4GL
Common Language Infrastructure – C#, Visual Basic .NET, J#, C++/CLI (formerly Managed C++)
Dalvik virtual machine – part of the Android mobile phone platform
Dis – Inferno operating system and its Limbo programming language
Eiffel Studio for the Eiffel programming language
Erlang programming language
Forth virtual machine – Forth
Glulx – Glulx, Z-code
Hec – Hasm Assembler
Java Virtual Machine – Java, Nice, NetREXX, Scala, Groovy, Clojure, JRuby
Juke Virtual Machine – A public domain ECMA-
Low Level Virtual Machine (LLVM) – currently C, C++, Stacker
Macromedia Flash Player – SWF
p-code machine – Pascal
Parrot – Perl 6
Smalltalk virtual machine – Smalltalk
SQLite virtual machine – SQLite opcodes
Squeak virtual machine – Squeak
Val grind – checking of memory accesses and leaks in x86/x86-64 code under Linux
Virtual Processor (VP) from Tao Groumadarchodp (UK).
VX32 virtual machine – application-level virtualization for native code
3. Benefits of using virtual machine
This section describes the benefits of virtual machine technology that benefits the user:
In virtual machines the physical resources are shared in a single computer, they remain altogether isolate from each other as whenever they are classify physical machines. Executing all applications in a particular machine it’s a great work by virtual machines sometimes they faced the undesirable interactions, because of software applications problems and isolated security.
Fig 4:- isolation in virtual machine
virtual machine Allow all group of applications isolate in an own sandpit environment, the virtual machines are run on the same physical machine but they appear as a some other machines when software is running for that purpose the performance of the virtual machines are yet to be an independent machines. For e.g. if three or four virtual machines running in the same physical machine if one virtual machines crashes other three virtual machines providing services and function smoothly. In virtual machine isolation is a crucial role when multiple operating systems running in the same physical computer to compare the security and availability of the applications in the virtual environment.
In a physical computer is executed by a particular operating system like that a virtual machine has its own operating system and executed by multiple operating systems by their guest operating system and executed by its own applications
the components what it supported to physical computer like: mother board, network card controller and VGA card etc. that has supported to virtual machine also, so far virtual machines are equally standard to normal physical computer and supports all x86 versions of operating systems generally execute the normal applications and system drivers, so we can run the virtual machine by using all software components that you would execute on the physical x86 computer.
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In a virtual machine a complete set of virtual hardware resources that encapsulates in a single software container. As well as all applications in an operating system inside a software package that encapsulates builds virtual machines incredibly easy to manage and portable, means we can copy and move the software files in virtual machine from one location to another location or else we can saved the data in any standard data storage medium like USB flash memory card.
We can built a virtual machines with virtual components like CPU, network card, SCSI controller, so virtual machines are completely autonomous from their underlying physical hardware.
Fig: 5- hardware independence
In a physical computer we can’t configure virtual components to execute a software component but in virtual machines it’s possible to create a virtual environment. But in the virtual machines on the same physical server we can run different operating systems like windows xp, 2007, Linux etc.
Ease of Testing:
In virtual machines we can installed multiple platforms so they are independent to each other, so far IT administrator to test of one software applications in one virtual machines without interrupting the work of other virtual machines. This is one of the great advantages of the newer software versions which will be installed in a particular machine for testing without interrupting work on other virtual machines.
While observing all the above benefits of the virtual machine its is compatible with all x86 computer versions and freely move to one virtual machine to another machine without making any changes of operating systems or system applications. Independent hardware as well intends that we can run different operating systems or software applications on a single computer.
4. Drawbacks and Challenges of virtual machine technology:
In a virtual machine for designing a software and be installed in the virtual machine the licensing cost is too high while compared to normal physical computer it’s the drawbacks in virtual machine technology. If we run the virtual machine software’s in servers on virtual machine ware’s GSX server or more the cost of the physical hardware established on physical machine specifications.
Presently virtual machine runs only on Linux hosts because xen charges no license fee and deals only guest operating systems for that source code is available, that standards are admit only in Linux and BSD but not in windows. To execute unmodified guest operating systems means xen be able to run on windows, the Intel is soon being released virtual technology and AMD in Pacifica chip technology.
VM technology is usually reducing the debugs when it is spread in right configuration. When we compare x or x virtual machines some physical machines are higher in n number of virtual machines in the hosting process.
In virtual machine technology running and additional guest operating system on the physical hardware, the performance penalty varies on the virtual machine due to a guest operating system. In VMware workstation due to an additional guest operating system the processor slows down up to 88 percent on I/0 bound tasks.
To improve the virtual machine technology in the performance penalty we need to purchase additional hardware, higher-end hardware to increased the ease of management and the performance penalty much heavier than the license fees and potentially require more hardware requirements per physical machine.
In the virtual machine technology it holds only the hardware that endures both guest operating system and virtual machine hypervisor. Yet the guest operating system holds the physical hardware, but the virtual hardware is handled by virtual machine.
The guest operating system is in the hardware which supports by virtual machine hardware. It’s not the matter of hardware in the host and also the guest environment presented by hardware and normally the same.
It is one of the drawbacks in virtual machine technology for software licensing within guest operating system it’s too cost. If we install and execute the windows in eight virtual machines on six physical machines we have to buy a licensing for virtual machine software to install the software based on the number of processors. If it has a dual processor in physical machine for only in one processor, if the virtual machines is runs by oracle software they charged for only one processor.
Xen is virtual machine monitor titanium, IA-32, x86-64 and ARM architectures. In the same computer it allows several guest operating systems concurrently. The structure of xen systems with the xen hypervisor is lowest and most privileged layer. On the top of this layer one or more is operating systems, which it schedules across the physical CPU. In xen terminology the first guest operating is “domain0″it boots automatically when the xen receives special management privileges by default it directly access all physical hardware. “Domain u” in the xen terminology when the system administrator can log into domain 0 to manage further guest operating systems.
Fig 6:- xen architecture
In the “domain 0” we can run the upgraded versions of Linux, NetBSD and Solaris. Various modified versions like UNIX operating systems might be function as guest operating systems on a particular hardware systems of using the version 3.0 for xen sources, but in unmodified versions of Microsoft windows and other operating systems can also be run as a guest operating systems if the cpu supports x86 hardware.
Virtual machine monitors are classified into two types Type 1 and Type 2 hypervisors.
Type 1 virtual machine monitors are run directly into the host hardware to handle the hardware and monitor the guest operating systems, but a guest operating systems be run in another level of the hypervisor.
Type2 virtual machine monitors are run within its operating systems. But guest operating systems run at the third level over the hardware.
Ms Windows’s system as guests:
If the host machine’s processor bears hardware virtualization permitted by Intel VT-x or AMD-V.The unmodified version of Microsoft Windows as a guest operating system is capability to run on Xen version 3.0
Unix-like system as a guest:
To execute guest operating systems for fully virtualized we required special hardware and for par virtualized to require guest Operating system adjustment. The following system has plots leaving them to run paravirtualized Xen guests:
paravirtualization,Linux merged in 2.6.23, patches for other versions exist
Plan 9 from Bell Labs
OpenBSD, announced here but discontinued
OZONE (has support for Xen v1.2)
Finally we conclude that virtualization have a future while comparing all the benifits and feautures of virtualization.Virtualization is a process where we can dump or make a snapshot of our entire personal computer in which the data can be copied to another personal computer or machine in a very fast process that is in minutes and can do our work right off.
There are various programming software’s which gives the ability to access on any kind of familiar operating systems like Mac, Linux or PC.
The main reasons to use virtualization in this computer are given a few reasons below:
Portable workspaces-virtualization USB memory sticks the whole data in digital format can be dumped from one machine to another physical machine and work out directly.
Testing and training- when we load different software programs to other personal computing environment ,we can test the programming using virtual machine we could test for different categories which when for games, one machine for the personal computer and even for machine for work.
Disaster recovery- when the whole data expires in your personal computer when we use the given back up to your virtual machine like easy handled USB hard drive to use the system data which we need to work out where we got struck within the system .We even no need to reinstall the whole thing from the beginning.
Fig 7:- backup of entire virtual machine
Consolidation-Virtual Machines usually strength several physical servers to lesser servers while they simultaneously host virtual machines. Every physical server is bent back i.e. reflected like guest which stays on virtual machine host system. The whole system is also known as physical -to Virtual or P2V transformation.
When most of the programming and human factors in coding is that firstly some of the code makers usually for very small extension or a larger product like team system
In future quad -core chips are yet to be available in the desktop system and duel core will be on new personal computers.
New CPU will accelerate VM: The fastest machines these days are Virtual machines declared after the reasonable research. The intel and AMD are having vanderpool and Pacifica technologies respectively which are helpful to speed up virtualization.
OS does not consider: When virtual machine does the pre configuration with in a fraction of second no one is bothered in which platform it is done like OS or Linux is no where considered.
The software installation a no -brainer: When the installation or setup.exe files are not installed we can boot using the virtual machines which has programming software’s stores in it with secure keys in it loaded.
Extremity insecurity sandbox’s single virus can’t even escape from virtual machine software when we complete the program just run the software after any OS session is completed for every start up you can have a new VM. This process resembles the formatting of pen drive .
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