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What is a Virtual Machine?
Virtual machines (VMs) are computers but without physical chassis, monitors, chips, boards, and wires. They’re made entirely of code, and that confers a lot of flexibility. Like any office laptop, personal tablet, or data center server, they have a central processing unit (CPU), memory, ‘disks’ where files are stored, and an Internet connection.
What they need is space, a plug or power socket, exterior cooling, or a specific operating system (OS). They give IT teams huge flexibility in how they deploy computing resources, and they’re perfect for cloud computing.
Key Takeaways
- Virtual machines are digital versions of physical computers.
- They can do everything a physical computer can do – run programs, run operating systems, store data, and connect to networks.
- However, the computing resources a virtual machine uses are entirely software-driven.
- VMs let developers create safe environments for testing and trialing new applications.
- In cloud computing, VMs enable the multi-tenant cloud architecture that allows data and applications to be used by thousands of people all at once.
How Virtual Machines Work
In a typical setup, one or more virtual machines (sometimes called ‘guests’) run on a physical ‘host’ computer. Each virtual machine has its own operating system and works independently of the others, despite running side by side on the same host machine. In practice this means that a virtual Linux machine could run on a Mac host, or a MacOS VM could run on a PC host, and vice versa.
There are many advantages to this. Cloud computing services, for example, use virtual machines to deploy applications to multiple users simultaneously. Because VMs ‘borrow’ available resources from the host machine’s processing, memory, and storage capacity, IT teams can use any dormant compute power to scale service levels up or down in line with demand – without continually having to purchase new kits.
What are Virtual Machines Used For?
Virtual machines are often used in server virtualization, an approach that allows IT teams to make use of all the unused capacity sitting inside their existing physical machines and maximize efficiency. VMs can also be used for higher-risk activities that might create instability in a live IT environment.
These could include:
- Trialing a new operating system or the beta release of a promising new application.
- Create a test environment for developers.
- Backing up an organization’s current OS.
- Running an older version of an application on an older OS to access legacy files.
- Accessing virus-infected data.
- Running software or applications on operating system, they wouldn’t normally be compatible with.
Types of Virtual Machines
There are two types of virtual machines: process virtual machines and system virtual machines.
Process virtual machines support a single process and run as standard applications inside the host machine’s operating system. Sometimes called managed runtime environments (MREs) or application virtual machines, they launch when the process starts and demobilize when it finishes. The main advantage of a process VM is that the process in question can run in any programming environment and execute in similar ways across multiple platforms.
System virtual machines completely virtualize real computers, replacing physical machines with software and eliminating the tangible constraints that come with hardware, power, operating systems, and maintenance. The (physical) host machine’s resources can be shared and managed by more than one system virtual machine, allowing multiple environments to live on on the same host system. The VMs work side by side, but separately, enabling more than one single-tasking OS to use resources at the same time.
VMs Pricing
Cloud providers offer virtual machines in a range of pricing models. Major providers like AWS and Microsoft Azure offer virtual machines on a pay-as-you-go (PAYG) basis, as an add-on to other cloud application services, on a reserve basis where they switch on automatically when required, or as a ‘spot’ purchase when absolutely necessary.
5 Things to Consider When Choosing a Virtual Machine Provider
Virtual machines can simplify many things for IT teams, but the selection process isn’t so simple. There are a number of features and capabilities to consider in the context of your organization’s specific needs and budget:
Performance
VMs need high processing power and memory to handle resource-intensive applications.Scalability
VMs should be able to scale up workloads quickly as the business and activity levels grow.Security
Any VM provider should offer robust security protections, including data encryption that complies with industry standards.Ease of Use
VMs should offer straightforward configuration and management.Cost
Usage of VMs compute resources will be variable, so calculating total cost of ownership (TCO) is essential to understanding the true cost.
Virtual Machine Use Cases
VMs offer different advantages in different scenarios.
Some of the most popular virtual machine use cases include:
Virtual Machine Examples
VMware Workstation Player enables seamless data sharing between hosts and guests and is built with IT professionals, supporting multiple operating systems on one host machine without the necessity of a reboot.
Parallel Desktop VMs allow Windows applications to run on a Mac machine without rebooting. They enable single-click switching from Mac to Windows and support platforms including Windows 11,10,8.1, and Windows 7, Linux, and macOS.
OracleVM VirtualBox is for home and enterprise use. Home users benefit from an intuitive interface and an easy-to-follow guide for adding new virtual machines. Enterprise users benefit from high performance and compatibility with most versions of Windows.
Citrix Hypervisor simplifies VM administration and makes it easier for IT teams to conduct resource-intensive tasks in a virtualized environment. It is known to be useful for enhanced graphic workloads and giving users a secure environment to store, access, and use large files.
Virtual Machine Pros and Cons
Virtual machines are easy to manage and maintain and offer other advantages that physical machines can’t; however, there are also downsides to consider.
- VMs allow multiple operating systems to run on a single physical computer, saving space, maintenance, and hardware costs
- VMs allow you to use older versions of applications, reducing the cost of moving to a new operating system
- VMs enable IT teams to maximize the value of existing IT investments
- VMs need a robust infrastructure to operate in a stable fashion, so the host machines need high-performing chips, GPUs, memory, plus the latest virtualization and management software
- Virtual machines can be less efficient and run more slowly than physical machines. Many organizations use a blend of physical and virtual servers to keep workloads in balance
The Bottom Line
While computer virtualization was first pioneered in the 1960s, digital transformation and the continuing shift to the cloud have made VMs an essential part of 21st-century computing.
Today’s organizations need fast scalability to maximize the value of their IT investments. The ability to use multiple operating systems and draw computing resources from disparate systems are crucial advantages as digital business processes move to the forefront.
