What Is a Virtual Machine?
When most people think of virtual machines, they tend to think of those once-futuristic virtual reality sets or a way to play old video games on your modern computer. But those aren’t the virtual machines we’re talking about here. So, what is a virtual machine exactly, and what do they have to do with developers?
We all swear by our operating systems. Whether you use macOS, Windows, Linux, iOS, or Android, you probably have a list of reasons why your operating system is superior. That’s okay — we’re the same way.
But, if you’re going to make it as a developer, you’ll have to explore other operating systems if you want your applications and web pages to work everywhere. If you’re working on a Mac, how exactly will you know that your program works in Windows? And who’s to say that the amazing web app you designed for Android will look the same in iOS?
This is why developers love virtual machines. And, after reading this article, you will too once you understand what they are, how they work, and why people use them.
Your operating system and you
Before we get into the details of virtual machines, it’s important first to understand what an operating system is and how it works.
Computers, smartphones, and tablets are all made of physical components or hardware. Hard drives, processors, batteries, fans, and memory cards are all part of the hardware.
An operating system (OS) is software that directly controls the hardware components in your computer or device. macOS, Windows, Linux, iOS, and Android are all programmed to control hardware in different ways.
When you use an application on your computer or device, your OS uses the device’s hardware components to run that application.
What is a virtual machine?
As long as your computer or device has the hardware capacity — enough memory, processing power, and so on — you can run just about any application through your OS, as long as the software code is compatible with it. You could even run an application that looks and feels like you’re using an entirely different OS.
And that’s exactly what a virtual machine is. It’s a software application designed to look and run like an OS different from the OS installed on a computer, mobile device, or even server.
How a virtual machine works
To run a virtual machine (VM), you need to work with a host computer or server that provides the hardware resources. This is called the host machine. Each virtual machine on a particular host machine is called a guest machine.
To manage hardware resources, host machines and guest machines rely on a special type of software called a hypervisor. A hypervisor partitions — or reserves — some hardware capacity for the virtual machine, such as CPU, memory, and storage. That way, the virtual machine is kept isolated from the rest of the host machine system.
When you use a virtual machine, the operating system will only recognize the resources allocated to it. For example, if you have a computer with 16 GB of RAM and your hypervisor gives 4 GB of RAM to the virtual machine, then the system settings in your virtual machine OS will show that you’re using a computer with 4 GB of RAM.
If the virtual machine requires more than its allocated resources at any point, then the hypervisor manages the request to ensure that the host machine is always performing within its limitations.
Why use a virtual machine?
Anyone involved in software development — Front-End Developers, Back-End Developers, and Full-Stack Developers — can benefit from using a virtual machine. That’s because VMs offer a lot of testing flexibility. You can even break things without consequences!
Here are the biggest advantages of virtual machines:
Run multiple operating systems at the same time
The biggest advantage of using a virtual machine is running another — sometimes several — different operating systems at once. The only limiting factors are the hardware resources of the host machine.
This means that whenever you’re developing applications or software, you can effectively test your work on multiple operating systems without having to buy another physical machine or use a different server.
Access the power of a server from anywhere
If you’re using a server or host machine, then you have access to the server’s processing power as long as you have an online connection to it. Theoretically, you can write, run, and test high-performance programs from a laptop or even a tablet.
Complete system isolation
If you’re designing an application, the last thing you want is for the program to crash your entire system because of a bug you overlooked.
Virtual machines give developers a virtual sandbox to test their applications before running them directly on a physical machine. If there’s a disk crash within your virtual machine environment, it won’t affect the disk’s partition of the host machine.
Disadvantages of virtual machines
Although virtual machines offer plenty of advantages that make them a great choice for developers, they don’t offer the perfect solution. In particular, virtual machines reduce system efficiency and add network complexity.
Virtual machines are less efficient
When you run an application on your computer’s native OS, the OS can directly access the computer’s hardware resources. But, with a virtual machine, partitioned hardware resources are available only indirectly. When you run an application on a virtual machine, the VM first requests access to hardware resources through the host machine OS. This makes virtual machines slower and less efficient than if they were running as a native-installed OS.
Virtual machines add network complexity
It can be challenging enough to manage and secure a network of physical machines, and adding virtual machines doesn’t make it any easier. If you’re planning to use a virtual machine in your next development project, make sure you’re ready to do a little extra IT work to keep your VM secure or talk to your IT team.
Use a virtual machine for your next development project
If you’re not sure how to get started with your first app, take a look through our Career Paths. We’ll help guide you toward picking up the skills you need to succeed in your new development career.