Concept about Virtual Machines

1. Virtual Machine Concept

2. • A Virtual Machine (VM) is a software program or operating system
that not only exhibits the behavior of a separate computer, but is also
capable of performing tasks such as running applications and
programs like a separate computer.
• A Virtual Machine is also known as “Guest”.
• It is created within another computing environment referred as a
“Host”.

3. Types Of Virtual Machine
System Virtual Machine
Process Virtual Machine

4. System Virtual Machine
Also known as Hardware Virtual Machine.
Allow the sharing of the underlying physical machine resources
between different virtual machines, each running its own
operating system.
 The software layer providing the virtualization is called a
Virtual Machine Monitor or hypervisor.

5. Process Virtual Machines
Also known as Application Virtual Machine
 Runs as a normal application inside an OS and supports a single
process.
It is created when that process is started and destroyed when it exits.
 Its purpose is to provide a platform-independent programming
environment that abstracts away details of the underlying hardware or
operating system, and allows a program to execute in the same way on
any platform.

6. Advantages
Familiar Interface
Isolation
High Availability
Scalability
Backup with Fast Recovery
Reduction of Cost

7. Disadvantage
Difficult in direct access to hardware.
Capacity of RAM should be larger.
Capacity of Disk should be larger.
A Virtual Machine is less efficient than an actual machine when it
accesses the host hard drive indirectly.

8. Examples
XEN
Virtual Box
VMware Workstation
Citrix