The hypervisor

The hypervisor

The hypervisor

I never realised until today just how many hypervisor options are out there. Not only how many but that there are different types as well. Obviously I had heard of the industry standards ESXi and the Microsoft alternative Hyper-V but little did I realise that is only scratching the surface. You’ve also got XenServer, Proxmox and KVM just to name some of the more popular hypervisor options. In the last few days I have managed to go from having a good idea of what I wanted to implement, to landing myself in a vast sea of information that just seems limitless. Each hypervisor has it’s benefits and limitations when compared to it’s competitors so I have a lot of research to do before making my final decision and sticking with it. So let’s start with the basics:

What is a hypervisor?

A hypervisor is a piece of software that can create and run virtual machines. The computer or server that this software runs on is known as the host, and the virtual machines are known as guests. A certain defined portion of the resources from the host machine such as memory and disk space are allocated to a guest machine to use. These guest machines have no idea that they do not own these resources – As far as the VM (Virtual Machine) is concerned it is a single independent entity. The hypervisor is actually controlling the resources of the host and distributing them as required.

There are in fact two types of hypervisor – Type 1 and Type 2. What type you choose really doesn’t matter as they serve the same purpose, but for educations sake the distinction is there. A type 1 hypervisor is commonly known as a ‘bare metal hypervisor’ because it runs directly on the hardware of the host. In other words there is no operating system or any other software in between the hardware layer and hypervisor.

hypervisor type 1
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The other type is a Type 2 hypervisor, commonly referred to as a hosted hypervisor. This is software that runs on an operating system. One of the more common examples of this would be Oracle Virtualbox or VMware Workstation. I guess the main disadvantage of a hosted hypervisor is that you are adding an unnecessary extra layer to the environment. However this has the benefit of making management somewhat more intuitive in my opinion.

hypervisor type 2
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Which is the best hypervisor option?

If you find out please let me know! Generally people are quick to recommend ESXi due to the fact it has more or less become the industry standard and having experience in such a widely used product would be beneficial. This was part of my original reasoning behind ESXi because I do encounter it frequently in work but I don’t have a whole lot of experience working with it. It makes ESXi very hard to ignore for this reason, but on the flip side the possibilities are somewhat limited without purchasing a license. I’m not going into the differences between the free and licensed options in this post, but it is definitely something I am going to do in the future.

Then of course you have Hyper-V, another very commonly implemented option from Microsoft. This has the massive advantage of being free and comes bundled with Windows Server as an add-on feature. If you are running Windows 8 at home you can also enable Client Hyper-v which isn’t as feature-filled as the Server alternative but offers the same purpose. Finally you have your Linux alternatives which are also mostly free if you are not interested in receiving support. These options are much less widely used but are certainly growing in popularity.

I’ve got a lot of work to do….

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