Ø Virtual machine –
·
Virtual machine is a completely
separate individual operating system installation on our usual operating
system.
·
It is implemented by software emulation
and hardware virtualization.
·
A virtual machine usually known as
guest is created within another computing environment referred as host machine.
·
Multiple virtual machines can exist
within a single host at one time.
·
Virtual machine can be divided into two
category –
a.
System virtual memory
b.
Process virtual memory
1) System virtual memory –
·
It provides a complete system platform
that executes complete operating system.
·
System plate form that support the
sharing of the host computers physical resources between multiple virtual
machine.
·
Each running with its own copy of the
operating system.
2) Process virtual memory –
·
Process virtual machine will run a
single program(multiple job)
·
Design to provide a plate form
independent programming environment.
Advantages /benefits of virtual memory
–
·
Multiple operating system environments
can exist simultaneously on the machine, isolated from each other.
·
Virtual machine can offer an
instruction set architecture that different forms real computer.
·
Easy to manage and maintain.
·
Widely available.
·
Allow disaster recovery option.
Disadvantages of virtual machine –
·
Multiple virtual machines running on a
single physical machine can deliver unstable performance.
·
Virtual machine is not efficient when
accessing the hardware.
Different between open source and
closed source- Open source operating system are those
available in source code format rather than compiled binary code.
Linux
is the most famous open source operating system while Microsoft window in a
closed source approach.