Virtual Machines

• Brief Overview:
• Highest level -two types.  Machine/system VMs or Process or application VMs.
• VirtualBox ....  the java RTE
  
• Fundamental idea – abstract hardware of a single computer into several different execution environments
• Similar to layered approach
  
• But layer creates virtual system (virtual machine, or VM) on which operation systems or applications can run
  
• Several components
  
• Host – underlying hardware system
• Virtual machine manager (VMM) or hypervisor – creates and runs virtual machines by providing interface that is identical to the host (Except in the case of paravirtualization)
• Guest – process provided with virtual copy of the host Usually an operating system
  
• Single physical machine can run multiple operating systems concurrently, each in its own virtual machine
• Original concepts identified types
• Type 1 Hypervisor (also called bare metal or native) - KVM is an example
  Type 2 Hypervisor (also known as hosted hypervisors) -  VirtualBox is an example
• This article is an update to the definition of a VM - note the introduction of network virtualization !
  

VM systems

• Dates back to the 1960's with IBM's VM OS
• VMWare - first to make VMs popular in IT
• XEN -  a part of Linux
• Article on XEN
  
• KVM- Readily added to Linux
  
• Article 1 - KVM
  
• Article 2 -   native VMs for Linux
  
• VirtualBox =  The VM that we will use
  

This paper "The reincarnation of VMs"   was very good.... 15 years ago.

Since then 'containers' have been introduced as an alternative (or in addition) to VMs.     Dockers is likely the most popular form of containers.
The paper "A Comparative Study of Containers and Virtual Machines in Big Data Environment"  presents VMs in a more current context.

Last update: 8/30/2021