What is Hypervisor and how many types we got here? lets find out.

In the last segment, we discussed what virtual machines are and we talked about the idea of a Host. Likewise, we have clarified that there is Hardware, Software and a virtualization “layer”, which helps in creating and hosting the virtual machines. The virtual machines work within the Host, which is known as a hypervisor.

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The hypervisor itself is a software that is installed on the top of the layer of hardware, making the virtualization layer and which creates a platform for the VMs to be made on. Consider it a program instead of a physical part. It is important not to mix the concepts of Hypervisor with Operating system. Indeed, the Operating System is also a kind of software but it has its own job in processing and virtualization.

The hypervisor pulls the physical resources from the hardware and transforms them into virtual hardware. The hypervisor is the important key factor to make able virtualization, it’s what makes the virtualization layer. As the software must be installed to interact and use the hardware, the hypervisor must be installed to work with virtualization.

TYPE 1 HYPERVISOR

There are two techniques for installing virtualization on a system. The first technique is to install Type 1 Hypervisor software directly on the top layer of hardware. Now a question comes up, Doesn’t hardware needs an operating system installed onto it first? Actually there are different concepts, lets understand them in a better way.

The Type 1 hypervisor sits between the hardware and the virtual machine, which has its own one of a kind operating system which implies that the host hardware (a system) is not limited to one  operating system since it enables the system to have more than one  operating system at an instance on one system as virtual machines. With a Type 1 hypervisor, a system would now be able to run an operating system (suppose Windows) and furthermore at least one case of another operating system, for example, Linux Ubuntu, or any other version of Windows. Since the Type 1 hypervisor is introduced directly on the hardware, it is also known as Bare Metal Hypervisor. The following picture shows the layers of virtualization when using a Type 1 (bare metal) hypervisor.

One of the features of using a bare metal hypervisor is that any issues present in one VM do not interact with different VMs running on the hypervisor. This enables the client to run different programs at the same time on the VMs and perform multiple tasks without interacting or stressing over one of those programs crashing and preventing the various projects from working.

it should be clear from the picture above, there is nothing sitting between the hypervisor and the hardware, which brings up the issue of how a client expected to use the system without first experiencing the system’s OS? Keep in mind, the operating system makes the UI where a client simply needs to tap on symbols to complete everything.

To make it feasible for a client to interact with the bare metal hypervisor, the hypervisor incorporates a management program that makes a UI. Presently the client simply needs to tap the correct icons and set the settings to make and run VMs, such as using a standard work area i.e. Windows. Without this management program, you would simply get a dark screen when you turn on the system because there is no OS. For Example : VMware’s Type 1 hypervisor called ESXi, and the ‘Management Program’ is called vCenter. Others Type 1 hypervisor – Microsoft Hyper-V, Citrix/Xen Server,

In some settings, a bare-metal hypervisor is also referred to as an embedded hypervisor. This is because the hypervisor software is embedded in the hardware device.

TYPE 2 HYPERVISOR

The second technique for virtualization is called Hosted Virtualization or Type 2 Hypervisor. To set up a system with hosted virtualization, a Type 2 hypervisor called a hosted hypervisor should be installed on the top of operating system which has been already installed on the system, the host OS, not the top of hardware like in case of a bare metal hypervisor.

The host OS could be the Windows 10 on your system, the Apple OS X on your system at work, or any other old version of Windows.

The Hosted (Type 2) Hypervisor relies upon the host Operating System to give direct access to the system’s hardware resources and deal with those resources to make virtual machines. For instance, if you had a system running Windows 10 as an OS, you would introduce the Type 2 hypervisor directly onto your system using the standard installation process like downloading and installing.

Fig.2. Type 1 Hypervisor

The best part about the Type 2 hypervisor is that it is very easy to download and enables you to begin playing around with virtualization by making your own virtual machines. Despite the fact that there are a couple of steps required before you can really launch and use the VM, you don’t have to be an IT engineer for all this.

There are two Hosted hypervisors accessible to download through VMware; VMware Workstation and VMware Fusion. If the system being virtualized is running a Windows or Linux operating system, the client would need to download VMware’s Workstation as a Type 2 hypervisor and if the system being virtualized is a MacOSX system, VMware’s Fusion hypervisor is the Type 2 hypervisor is good with system.

To put it plainly, Workstation is for making VMs on Windows or Linux and Fusion is for making VMs on a Mac. Both Fusion and Workstation work as the ‘Host’ and both are Hosted hypervisors that you introduce over the previously existing host OS. Other Type 2 Hypervisor – Microsoft Virtual PC, Oracle Virtual Box.

TYPE 1 VS TYPE 2 HYPERVISOR

1. Type 1 operates directly on the hardware of the host and can observe the operating systems that keep running over the hypervisor. But in the case of Type 2, the hypervisor is installed on an operating system and after that it supports other operating system on top of it.

2. Type 1 does not depend on any Operating System but Type 2 completely depends on host Operating System for its operations.

3. A significant advantage is that any issues in one virtual machine or host operating system do not interact with the other host operating system running on the Type 1 hypervisor. But in the case of Type 2, any issues in the base operating system would affect the whole framework, also regardless of whether the hypervisor running over the base OS is secure.

FINAL WORDS

Taking everything into short, Hypervisor is capable for making and executing virtual machines. There are two kinds of hypervisors as Type 1 and Type 2. The primary distinction between Type 1 and Type 2 Hypervisor is that Type 1 Hypervisor runs directly on the host’s hardware while Type 2 Hypervisor keeps running on an operating system like other system programs.

If you have any suggestion or any thought, just comment down below.

More on Virtualization concepts :

1. What is Virtualization? Basic Virtualization Understanding Part -1

2. What is a Virtual Machine? Basic Virtualization Understanding Part -2

Biplab Das

Biplab Das

My name is Biplab Das. I’m a writer, Blogger, Programmer, ICT tutor and a part-time website developer whose childhood obsession with science fiction never quite faded. A quarter-century later, the technology that I coveted as a kid is woven into the fabric of everyday life. I’ve spent the past years to learn these technologies, i recently published a book on computer science fundamentals. People say smartphones are boring these days, but I think everyone is beginning to take this wonderful technology marvel for granted.
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