What is a hypervisor? Virtualisation 101

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    Despite how the word sounds, hypervisors are relatively straightforward to understand. They allow you to create and control Virtual Machines within your hardware which lets you run multiple Operating Systems (OS) at once.

    Hypervisors first arose in the 1960s to allow for different OS to run on the same server system. However, their current popularity is due in large part to Linux and UNIX systems. The open source nature of these systems has allowed for a large amount of third-party integration, which has also prevented there being an overall market leader.

    So what exactly is a hypervisor and why is it so popular? Let’s dive deeper into the basics.

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    Hypervisors: the basics

    A hypervisor is a layer of software that allows for hardware to run two OS simultaneously in a virtual environment. This means that you’re using the entire computing power of your machine.

    Usually, a single OS does not utilise the entire potential of the computer’s hardware. But with a hypervisor, you can manage and use the entirety of your physical hardware. These OS programs come as Virtual Machines (VMs) and mimic the hardware of an entire machine in software.

    The hypervisor’s primary function is to manage those machines, becoming a Virtual Machine Monitor (VMM). The hypervisor manages the physical machines, allocating hardware resources to ensure they run smoothly, whilst also ensuring that they do not interact with one another in a way that interferes with their operations. It assigns them individual portions of memory, storage and computing power logically to ensure that all the operating systems run correctly.

    There are two different types of hypervisors, Type 1 and Type 2, each with different installation methods, and with positives and negatives attached.

    Type 1 hypervisor

    A Type 1 hypervisor is also known as a bare-metal hypervisor. This type of hypervisor is installed directly onto the underlying hardware of a physical server. The bare-metal hypervisor then replaces the original OS software with itself, meaning that booting up any OS immediately engages the hypervisor.

    The benefit of this type of hypervisor is efficiency. The hypervisor launches immediately from the base hardware, which allows for faster load times and easier distribution of resources. It also increases their security as opposed to Type 2 hypervisors where there is no second layer of software between the hypervisor and the hardware that can be exploited. The downside, however, is that a Type 2 hypervisor requires a separate management system in order to control the host hardware and manage the VMs effectively.

    Type 2 hypervisor

    A Type 2 hypervisor is also known as a hosted hypervisor. A hosted hypervisor runs on top of the hardware’s OS, rather than being installed directly onto the hardware. Whilst bare-metal hypervisors are usually seen in servers, hosted hypervisors are more common on individual PCs that need to run multiple OS. For example, security running virus tests, or business users that need access to multiple forms of software that are only available on certain OS.

    A type 2 hypervisor allows for quick and easy access to guest OS that are hosted on a single machine. This makes for good end-usability as it allows for the consumer to cut and paste over OS, operate functions on separate VMs and generally allows for greater flexibility and multitasking.

    The downside, however, is latency. Having an OS running underneath a VM means that the hypervisor will not have direct access to the hardware, instead having to go through the host OS. This results in slower load times and limited distribution of hardware, and makes type 2 hypervisors slower and more vulnerable, as the hypervisor can be attacked through the host OS, creating a backdoor into the VMs.

    How to choose a hypervisor

    Hypervisors are, by and large, commodity products, but there are a few good ones to consider before purchasing. When looking at hypervisors, you need to consider a few things: Performance, ecosystem, management tools, migration and cost.

      • Performance: Hypervisors should provide benchmark data for their speeds at performing tasks and loading OS. You want to get a hypervisor that performs as close to native speed as possible, while also considering the type of hypervisor you are purchasing. When it comes to considering type 2 hypervisors especially, consider latency issues.
      • Ecosystem: Documents and technical support are all vital to managing hypervisors, especially if you’re deploying them at scale. Take care to note their after-sale services as well as third-party development.
      • Management Tools: These help you manage VM sprawl and ensures the smooth rollout of your hypervisors. Maintenance, provisioning and auditing your VMs must be done, which is why having good management tools is vital.
      • Live Migration: This allows you to move your VMs around between hypervisors and physical machines without interrupting them. This is useful for ensuring that hardware is not overworked.
      • Cost: When purchasing a hypervisor, remember to pay explicit attention to their licensing structures as well as the initial costs of the hypervisor.

    What are some good Type 1 hypervisors?

    There are a few good options when it comes to Type 1 hypervisors, such as VMware ESX, Microsoft Hyper-V and KVM.

      • VMware ESXi isn’t open source and based off of Linux Kernal, making it fairly easy to code.
      • Microsoft Hyper-V isn’t open source. It automatically installs Windows with the hypervisor and gives Windows more access to the hardware.
      • KVM is open-source so there is a wider range of third-party software and support. It’s based on Linux Kernal, meaning it’s easy to code.

    What are some good Type 2 hypervisors?

    When it comes to Type 2 hypervisors, your main players are VMware Workstation, Virtualbox and Parallels.

      • VMware Workstation has the edge when it comes to management tools. It is also better at supporting 3D graphics.
      • Virtualbox supports a wider range of OS, on top of the one you already have, supporting Linux, Windows, Solaris and FreeBSD. Being open source, it allows for more third-party integration than Workstation.
      • Parallels is dedicated to running guest OS on macOS. It technically competes with VMware Fusion rather than VMware Workstation.

    These are just a few examples of the different hypervisors on the market, so with the amount of choice there is, you’ll want to thoroughly research before you buy.

    Getting the right kind of hypervisor to suit your needs is essential — after all, it’s an investment you’re making in your business. And with remote working now the norm, there’s no better time to get the right virtualization tech.

    If you need more help with finding the right solution for you, we here at Nexstor can help — click here to learn more.

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    Troy Platts

    Troy has spent over 20 years helping organisations solve their data, storage and compute conundrums. He is a regular speaker at vendor events and spends any free time he has keeping abreast of advances in data platform technologies. He also makes a mean curry.

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