VMM: Virtual Monitor, also called Hypervisor, is a software layer in order to achieve virtualization introduced. It is actual physical control of resources down. Upwardly presented to the virtual machine parts N logical resources. To do this, we need to access virtual machines to physical resources "back door" ---- intercepted and redirected, so that the virtual machine mistakenly thought he was in exclusive physical resources.
The actual physical environment of the virtual machine monitor running, becomes host; out of the virtual logical host on which, called clients. Roger that
Ideally virtualization both a goal to be achieved:
1. Have the client does not know it is running in a virtual environment, I thought he was running in a native environment.
2. completely without VMM intervention process to run the client.
Paravirtualization:
Also known as the so-called para-virtualization (paravirtualization), it is to allow the client to mean that he is running in a virtualized environment, and handled accordingly to match the VMM.
Paravirtualized need to modify the client operating system (kernel modifications) to implement proactive notification. Typical paravirtualized virtio technique, using virtio are required on the drive mounted in a respective host / VMM and client in.