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What is virtualisation?

A guide to what virtual machines are and how they work

Using 'virtual' versions of physical things has become more and more popular in recent years, but what is virtualisation, exactly?

In essence, it's the process of turning hardware into a software equivalent without sacrificing functionality, the most common deployment being virtual servers instead of physical servers. It's largely used as a way of saving space, cutting costs, and improving functionality and security.

There's also the added benefit of creating extra capabilities on top of existing hardware. For example, virtualisation can be used to take the machine's storage or some of its capabilities and divide them across a number of virtual machines.

What is virtualisation?

The best way to think of virtualisation is to imagine five physical computers, each running their own isolated operating systems and software services. Each device can work separately on different tasks, but through virtualisation, you’re able to unlink each operating system (OS) and its software from each terminal and combine them into one single entity, or ‘host computer’. This can maintain separate software packages and run individual devices if it has to.

Separate virtual software instances are known as virtual machines (VMs) and are managed and coordinated by a single physical machine. This central computer utilises a ‘hypervisor’, which is a software platform the computer can use to manage the breadth of the VMs it runs. Through this hypervisor, it can share important elements like network bandwidth, memory usage, CPU cycles, as well as other computing resources.

These five computers we've imagined can, through virtualisation, be merged into a single combined machine while at the same time preserving their individuality, allowing workers to use them separately.

Virtualisation terminology

Virtual machines (VMs)

Virtual machines are one of the elementary units of virtualisation. This is best imagined as an independently functioning computer, except that it lacks a normally expected physical presence. A virtual machine, when deployed, can open an additional operating system on a single device, and that's including its own software.

The VM's working is independent of the host, meaning that it won't be affected if something goes wrong with the hardware used to access it. At the same time, since it's separate, the virtual machine can't influence the running of the 'host' computer.

Virtual memory

To ensure VMs work as smoothly as possible, it's pretty vital there's a high level of virtual memory available on the host computer.

This helps applications to improve overall performance and store and receive data. It's enabled by small additions to a machine's hardware, called segments or pages, that store the extra data a physical machine cannot.

Virtual desktop infrastructure

Virtual Desktop Infrastructure (VDI), is where an organisation purchases virtual desktops hosted by a third-party vendor and therefore don't have to deploy the technology on its on-premises infrastructure, lowering its costs and simplifying deployments.

According to Nick McQuire, VP of enterprise research at CCS Insight, the development of desktop as a service, or DaaS, is proving very popular.

"Virtual desktops and applications have been trending within enterprise IT for over a decade, ever since the growth in remote working has increased the need for mobile workstations, strongly encouraging many organisations to implement the technology," he says.

"As virtual desktops aren't hosted locally on the users' devices, an organisation can distribute stripped-down machines, known as thin clients, with access to company applications and data in the data centre to cut down on hardware costs and simplify management."

Virtual applications

Many of the merits of virtual desktops also apply to app virtualisation, which allows users to access apps without storing them locally and businesses to have more control over their usage.

"New uses of the technology have opened up the virtualisation of third-party specific applications such as Microsoft's Skype for Business or browsing," McQuire says. "Security requirements and compliance changes such as GDPR have also helped as more firms look for more control and visibility of the apps their employees use."

A folder labelled "GDPR Compliance" on a desk


"As more organisations look to upgrade the 300 million or more PCs in enterprises that are over five years old, they are embracing newer PC platforms. The likes of Google Chromebooks and Microsoft's Windows 10 are growing heavily in the public sector in the US."

What are the benefits of virtualisation?

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There are many benefits to be had from virtualisation; cost savings are arguably the most appealing, particularly given the expense of adding and maintaining more servers or desktops. Taking your on-premise servers and adding layers of virtualisation to them can transform your business by making your hardware work more efficiently or to a greater capacity, with very little financial outlay.

The fewer physical servers (or machines) in your building, the less time the IT department will spend on them, freeing their time for other, more critical tasks. It's also one less software licence to worry about, as well. What's more, if the server is faulty or no longer working, it will need to be replaced. Whereas a virtual server can be copied and re-deployed at its optimum state - the same is true for virtual machines affected with malware. Rather than physical damage, the affected VM can just be backed up, deleted and replaced with ease. That reduces the chance of costly downtime.

That also leads us to another benefit of virtualisation, its environmental impact. Without needing extra hardware, there is less demand for its manufacture, which also takes it away from landfills when it is eventually defunct. It also means less energy consumption as there will be fewer physical machines drawing power.

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