VIRTUAL MACHINE

What is VIRTUAL MACHINE ?

HERES' THE SECRET

                A self-contained operating environment that behaves as if it is a separate computer. For example, Jave applets run in a Java virtual machine (VM) that has no access to the host Operating system. This design has two advantages:

• System Independence: A Java application will run the same in any Java VM, regardless of the Hardware and Software underlying the system.
• Security: Because the VM has no contact with the operating system, there is little possibility of a Java program damaging other files or applications.

The second advantage, however, has a downside. Because programs running in a VM are separate from the operating system, they cannot take advantage of special operating system features.

System virtual machines

• multiple OS environments can co-exist on the same computer, in strong isolation from each other
• the virtual machine can provide an instruction set architecture (ISA) that is somewhat different from that of the real machine
• application provisioning, maintenance, high availability and disaster recover

The main disadvantages of VMs are:

• a virtual machine is less efficient than a real machine when it accesses the hardware indirectly
• when multiple VMs are concurrently running on the same physical host, each VM may exhibit a varying and unstable performance (Speed of Execution, and not results), which highly depends on the workload imposed on the system by other VMs, unless proper techniques are used for temporal isolation among virtual machines.

Multiple VMs each running their own operating system (called guest operating system) are frequently used in server consolidation, where different services that used to run on individual machines to avoid interference are instead run in separate VMs on the same physical machine.


Imp Note ::
                        If u have a windows 98 O.S running in your system :: just install virtual machine and you can run windows 7 and linux and evey O.S u want ::

Virtual machine is very helpful for the beginners who have started studying learning ethical hacking :::  make virus run on virtual machine this will not make any damage to your system

Virtual machine help to make work on any software :: it will help ya in everything you want ::

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