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Chaitanya Rahalkar
Chaitanya Rahalkar

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Understanding Virtualization in Operating Systems

XKCD
Virtualisation is the process of creating a virtual version of a physical object.

Virtualisation is of three types primarily:

  1. Hardware Virtualisation - Based on simulating real hardware. This can be used to run a complete operating system. This can be further subdivided into full and paravirtualisation.

  2. Desktop Virtualisation - It is the concept of separating the logical desktop from the physical machine.

  3. Operating system level virtualisation (also called as containerisation) - It is the operating system feature in which the kernel allows the existence of multiple isolated user-space instances. Such instances are called containers. Containerisation was introduced as a Linux Kernel feature in 2010. It started gaining momentum with the introduction of Docker.

Hardware Virtualisation

Some terminologies associated with Virtualisation:

  1. Virtual Machine: It is a virtual representation of a physical machine.

  2. Hypervisor: It is a software that manages and monitors running virtual machines.

  3. Host machine: The physical machine that a virtual machine is running on.

  4. Guest machine: The virtual machine running on the host machine.

The following block diagram shows the position of each component mentioned above:

Virtual Machine Diagram

Hypervisors

There are two main types of hypervisors:

  1. Native: They run directly on the host machine and share out resources between guest machines.

  2. Hosted: They run as an application inside the operating system and support virtual machines running as individual processes.
    Eg. VirutalBox,Parallel Desktop

Hypervisor Types

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