Hypervisor

From Vi-Pedia - Virtualization Wiki

A hypervisor is hardware virtualization software that allows multiple virtual machine to run on a single physical computer. A hypervisor is also called virtual machine monitor or "VMM".

Types of Hypervisors

There are two types of hypervisors, Hypervisor Type 1 (native, bare-metal) and Hypervisor Type 2 (hosted).

• A Type 1 (or native, bare-metal) hypervisor is a thin layer of software that runs directly on the physical host's hardware. It manages physical resources and also the interaction between the physical hardware and virtual machines. It is also responsible for monitoring the guest operating systems inside the virtual machines. A guest operating system (such as Microsoft Windows Server 2003 or Microsoft Windows XP Professional) thus runs on another level, above the hypervisor. This is the classic implementaion of virtual architectures. Examples of type 1of hypervisors are:
  • VMware ESX Server
  • Oracle VM
  • Microsoft Hyper-V
  • Xen
  • Citrix XenServer

• A Type 2 (or hosted) hypervisor is a software application that runs within a conventional operating system environment. Considering the hypervisor layer being a distinct software layer, guest operating systems thus run at the third level above the hardware. Examples of Tye 2 hypervisors are:
  • VMware Server (formerly known as GSX)
  • VMware Workstation
  • Vmware Fusion
  • Microsoft Virtual PC
  • Microsoft Virtual Server
  • Sun xVM VirtualBox