What Is Hypervisor And What Are Its Types

In this article, we covered what is hypervisors and what are their types. Also, we covered the most popular solutions for desktop, server virtualization, and hypervisors used by major cloud providers.

The hypervisor or virtual machine monitor (VMM) is a solution, which creates and manages virtual machines (VMs).

All VMs on the same physical computer share CPU, memory, storage, and network resources. Each of them, in this case, acts as a dedicated server with smaller compute resources.

The primary use case of this technology is the virtualization of servers and applications. And it is impossible to cover any Linux related topic without mentioning this one.

There are many different hypervisors available on the market:

  • Qemu KVM.
  • Oracle VirtualBox.
  • Parallels Desktop.
  • Microsoft Hyper-V.
  • VMware ESXi.
  • Citrix Xen.

Each of the products has its purpose. For example, ESXi, Hyper-V, KVM, and Xen are used for server virtualization. In comparison, VirtualBox and Parallels Desktop occupied the Desktop market.

The hypervisor’s general role is to provision, spin up, and retire the virtual machines as needed. Another critical feature of hypervisor is that it isolates virtual machines from each other and the host computer.

Functions of hypervisors

Some of the functions include:

  • Partitioning – split the host computer’s underlying hardware between different virtual machines.
  • Resources distribution – distribute CPU, memory, and network resources between other VMs.
  • VMs management – start, stop, and control VM lifecycle.
  • VM isolation – all VMs are entirely isolated; each VM has its own emulated hardware and OS.
  • VM communication – this feature controls how VMs connect to other VMs or hosts in the network.

Hypervisor Types

Hypervisors types

There are two types of VVM available – Type 1 and Type 2.

Type 1

Type 1 VMMs running on top of the physical hardware of the host. It is an optimized special-purpose OS with direct access to the hardware.

This leads to the primary benefits of any Type 1 solution:

  • Performance of the VMs.
  • Stability of VMs.

Here are some free and commercial product examples:

  • VMware ESX/ESXi.
  • Microsoft Hyper-V.
  • KVM.
  • Citrix.

Type 1 VMM share resources efficiently. They also show low latency and dynamic resource usage, and they enhance the communication between the host and the virtual machines and sometimes the communication between virtual machines.

Type 1 solutions help virtualize not only servers but the embedded systems such as robotic factory controllers. Many vendors use this technology to virtualize network equipment such as switches and routers too.

The primary use-cases for Type 1:

  • Systems consolidation – you do not have to buy new servers because you can increase available hardware utilization by creating multiple virtual machines. The main goal of virtualization is to consolidate servers within data centers.
  • Optimize usage of the physical resources – this naturally flows from the previous use-case; virtualization helps increase server utilization and accommodate additional applications. Save your money, time, data center space, and energy consumption.
  • Better resource allocation – You can manually and automatically manage resource allocation for your virtual servers or applications, which is the primary feature of any cloud.
  • Faster software development and testing – As a developer, you can deploy repeatable virtual environments for rapid feature development and testing.

Type 2

VMM of Type 2 is running on top of the operating system. They are easier to install and run than Type 1, as soon as it has a more complicated deployment and management process.

Type 2 solutions have limited access to the host computer’s hardware resources because the host OS manages access to the memory, network, and storage. That means VMs launched on top of Type 2 VMM always have a bit worse performance.

Besides, if the OS crashes, that hit the hypervisor too, and possible data loss might occur.

Here are some free and commercial product examples:

  • Oracle Virtual Box.
  • VMware Workstation.
  • Parallels Desktop.

Compare Hypervisors Types

One of the main advantages of Type 2 solutions is that they are easy to install. You can install them the same way you would any other software. Type 1, on the other hand, requires expertise, time, and money to deploy.

Type 2 requires extra overhead to run, and this makes them less efficient than Type 1. All applications running within the same OS as the hypervisor will compete for the same resources, which means that the VMs might run slow.

Desktop Solutions

There is plenty of choices to virtualize your desktop applications. Here’s the list of major players.

VirtualBox

VirtualBox is a free and open-source solution, and you can use it in Windows, Linux, or macOS. It is an excellent choice in most cases when you need to run two or more separate OS at the same time on your Laptop.

You can use it to run any desktop Windows version starting from Windows XP, any Windows server starting from Windows NT, Linux based on kernel 2.4 or higher, Solaris, OpenSolaris, and OpenBSD Unix.

Oracle supports VirtualBox. It is also well integrated with Vagrant, so you can download and use a wide selection of developer virtual machines.

Hypervisor - VirtualBox

Qemu KVM

Qemu KVM is a virtual hardware emulator that is also free to use. However, it runs on Linux only. This solution runs on top of x86 architecture and can emulate MIPS64, PowerPC, ARM, MicroBlaze, SPArc 32 and 64, SH4, ETRAX CRIS, and RISC-V.

Qemu can emulate VMs without the need for administrator privileges on the host OS. VMs perform as well as they would be installed on regular hardware and OS. However, Qemu doesn’t have sophisticated interface tools, and you will have to rely on CLI tools or APIs to deploy and configure virtual machines.

That is the primary hypervisor for open-source cloud computing platforms such as OpenStack and CloudStack.

Hypervisors - QEMU

Image source: commons.wikimedia.org.

VMware

The VMware Workstation Player is a solution that runs on Linux and x64 versions of Windows only. You can use it to set up VMs on a single host computer and then use them simultaneously. Each VM will have its OS, such as Linux, Microsoft Windows, and MS-DOS.

VMware Workstation Player is a free VMware product that you can use for non-commercial purposes. At the same time, if you’re interested in the features like Snapshots, enhanced network configuration, VM encryption, or running multiple VMs at once, I’d consider you to try VMware Workstation Pro.

Hypervisors - VMWare Workstation

Image source: commons.wikimedia.org.

Virtual PC

Microsoft Virtual PC is virtualization software that runs on Windows. It does not need hardware virtualization support, and it is free of charge for given editions of Windows. It comes pre-installed by OEMs, or you can download it at the Microsoft Website.

The new version of this solution offers seamless application publishing and launching, USB support and redirection, support for multithreading, smart card redirection, and swift integration with Windows Explorer. It has an intuitive file sharing interface where you can drag and drop files from one VM to another.

Parallels Desktop

Parallels Desktop is well integrated with macOS. It is not a free solution but is affordable, which makes it an ideal choice for personal use and small enterprises. One of the primary use cases for Parallels Desktop is to run Windows alongside macOS.

One of the unique features of this solution is that it can integrate Windows alerts to appear on the Mac Notification panel, allowing you to operate a unified platform.

While Parallels Desktop is synonymous with Windows for Mac, you can still use it to host other operating systems such as Linux distros and Chrome OS. You can run the basic or the Pro Edition, depending on your budget. The Pro Edition is ideal when you need to address more memory and support development environments such as Microsoft Visual Studio. You can also pick the Business Edition that adds centralized license management tools.

With the solution, you have access to usage stats and licensing activities in real-time. You can enroll users with ease through emails generated automatically through a few clicks. Switching process between Mac and guest virtual machine as easy as one click.

Hypervisors - Parallels Desktop

What is the best solution for my Desktop

As a Mac user, I do not see any other options other than to use Parallels Desktop. For any different use-case, I strongly recommend you to proceed with Virtualbox.

Moreover, it is the most popular Desktop hypervisor in the Wold, according to Google Trends.

What Hypervisors Are Used By Cloud Providers

Cloud providers logos

Amazon Web Services

Amazon Web Services is the biggest cloud provider in the world. It allows you to run your work online on a large scale. Today, AWS is a market leader in cloud computing, providing many services like no one else. Over the years, the AWS cloud has grown exponentially. And one of the most common questions is which technology do they use? AWS uses Xen (a highly customized version of Xen hypervisor). Starting from C5 instance types, AWS began to use Nitro, which primarily provides CPU and memory isolation for the EC2 instances.

Microsoft Azure

Microsoft Azure opened its services in 2008. Today Azure is one of the dominant cloud market leaders, and it competes with AWS and GCP for the cloud computing market share. Recently, Microsoft launched Azure Stack, which allows you to deploy some cloud services within your data center. Microsoft Hyper-V is powering Azure and Azure stack solutions.

Google Cloud Platform, GCP

Google Cloud Platform started providing cloud computing services in 2008, and they are competing for market share with AWS and Azure. GCP has an impressive list of features allowing them to be in a very competitive state in certain areas.

GCP chosen KVM as a primary technology for their cloud platform. Google runs its cloud computing with the conviction that everything and anything can and will run on the public cloud one day. So, they do not offer an on-premise solution.

Summary

There are many free and commercial virtualization solutions available for servers and Desktop markets right now. All of them allow you to run virtual machines or operating systems without purchasing new equipment.

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