VIRTUAL MACHINES IN OPERATING SYSTEM

VIRTUAL MACHINES:

·         Creating an abstract of a single computer (hardware) into several different execution environments, thus creating the illusion that each separate execution environment is running its own private computer.
·         By using CPU scheduling and virtual memory techniques OS can create illusion that a process has its own processor with its own memory
·         Virtual machine approach does not provide any additional functionality but provides an interface that is identical to the underlying hardware
The resources of the physical computer are shared to create the virtual machines.

    1. CPU scheduling can create the appearance that users have their own processor.
    2. Spooling and a file system can provide virtual card readers and virtual line printers.
    3. A normal user time-sharing terminal serves as the virtual machine operator’s console.

Advantages/Disadvantages of Virtual Machines


·         The virtual-machine concept provides complete protection of system resources since each virtual machine is isolated from all other virtual machines.
·         This isolation, however permits no direct sharing of resources.  
·         A virtual-machine system is a perfect vehicle for operating-systems research and development.
·         System development is done on the virtual machine, instead of on a physical machine and so does not disrupt normal system operation. 
·         The virtual machine concept is difficult to implement due to the effort required to provide an exact duplicate to the underlying machine.

Diagram:





No comments:

Post a Comment