Virtualization

Hypervisor

KVM and Xen are two highly relevant hypervisors. A hypervisor is software, firmware or hardware that creates and runs virtual machines as guests on a host machine. The hypervisor manages the execution of the guest OS's and the virtualized hardware exposed.

• Xen hypervisor is type-1, runs atop the hardware directly
• Virtualbox is a type-2 hypervisorthat runs on an OS as an application
• KVM blurs the lines between type-1 and type-2 b acting as a type-1 with a type-2-like interface for the user

full virtualization is where guest operating systems are unaware of each other and hypervisor directly interfaces with hardware resources.

• this offers the best abstraction in terms of isolation and security
• typically slower due to emulation involved

paravirtualization is where guest operating systems are aware of each other, allowing guest OS's to communicate with the hypervisor.

• efficient virtualization
• requires the guest os to be configured to interact with the para virtualization interfaces