What Is a Hypervisor? The Power Behind Virtual Machines

If you’ve read my piece on containerization (take 10 to 15 minutes from your busy schedule — you’ll thank me later), you may think virtualization is as outdated as baggy jeans!

Turns out, baggy jeans are trending again, and truth be told, while virtualization isn’t as fancy as containerization, it’s more like the combination of a black leather jacket and a white tee — its appeal is timeless (at least for the foreseeable future).

Of course, you can’t rock this attire when you’re attending a wedding or sitting for a job interview! Similarly, virtualization shouldn’t be used everywhere — it’s best suited to situations where strong isolation and security are the need of the hour. You may be thinking, “Why is he talking about virtualization when the topic of discussion is hypervisors?”

A hypervisor is to virtualization what a container runtime is to containerization, and more. It’s software that enables the creation, management, and execution of virtual machines (VMs) on physical hardware (the host system).

Whether you prefer a suit with bold patterns and prints (an apt fashion correlation for containerization) or a leather jacket, one thing’s for sure: you’re going to enjoy how I’ve “dressed” this article!

You already know that a hypervisor manages VMs, so I’ll address its importance by taking the example of an in-house server environment. Have you heard of the term “server utilization?”

It’s a measure of how efficiently your server resources are being used. If you want to maximize resource utilization on physical machines like computers or servers, you need technologies like virtualization.

To put it into perspective, your servers are idle 75% of the time! That’s a lot of wasted energy (your servers are up and running 24/7).

To illustrate, if your server has a total of 16 gigabytes of RAM and eight CPU cores each, you can use a hypervisor to create virtual machines and adequately allocate resources to these VM instances to maximize server efficiency.

That’s better than dedicating the server to run a single heavy application that uses 15 gigabytes of RAM and seven CPU cores — the goal is to reach server utilization of close to 100%.

Now, the real question is, how do hypervisors abstract hardware resources and distribute them among multiple VMs? For starters, you need to know the hypervisor sits pretty between physical hardware resources (such as CPU cores, RAM, and storage) and virtual machines.

You can think of it as a landlord managing tenants (VMs) in an apartment building (physical server). Here’s how the “landlord” allocates the perfect apartment (resources) to VMs:

• When you access the graphical user interface (GUI) of a hypervisor like Microsoft Hyper-V to create a new VM instance, you can request the hardware resources you need for it.
• If you didn’t know this already, virtual machines function as virtual computers (or mini-computers), complete with their own operating system (irrespective of the host OS). This means you need to specify resources like the virtual processors, RAM, size of the virtual disk, and virtual switch for your virtual machine.
• The hypervisor will then interact either directly or indirectly (through the host OS) with the hardware resources — more on this in the next section — to provide these virtualized resources to the VM.

Once the hypervisor has created your VM, it’s like an empty computer waiting to be “booted.” You can install the operating system (OS) of your choice on the VM and use it by logging into the guest OS.

You might find this funny: the two types of hypervisors are literally called Type 1 and Type 2! Talk about a lack of creativity (just kidding).

If you prefer a brawny build, Type 1 hypervisors are your go-to. They’re like the bare metal boss. On the other hand, if a lean physique is more to your liking, Type 2 hypervisors are the one for the job.

You can think of them as a friendly sidekick. If this sounds like gibberish to you, let me simplify things. Read on!

Type 1: Bare-Metal Hypervisors

Type 1 hypervisors, or bare-metal hypervisors, are in charge of keeping everything in line and run directly on the physical hardware of your computer.

They’re pretty cool, as they don’t need an underlying OS and are faster and more secure than Type-2 hypervisors. Since Type-1 hypervisors interact directly with your hardware, they’re perfect for businesses that need to run multiple VMs simultaneously.

Examples:

• VMware ESXi
• Microsoft Hyper-V (my personal favorite)
• Xen

But what if you’re a beginner? You may find it difficult to set up a Type-1 hypervisor for your system. That’s where Type-2 hypervisors come in handy.

Type 2: Hosted Hypervisors

Type 2 hypervisors, or hosted hypervisors, run on top of your existing operating system, which means it’s basically like any other software on your computer. It’s the “software within software” approach.

Since all resource allocations are mediated by the host OS, Type-2 hypervisors are generally slower than their counterparts.

Examples:

• VMware Workstation
• Oracle VirtualBox

On the plus side, they’re super easy to set up and use, and as you may have guessed already, are ideal for personal use or small-scale testing.

Bare-Metal vs. Hosted Hypervisors

VMware Workstation Pro is now available for free for personal use. If I were you, I’d check it out!

Where do I start? Whether you’re working on a personal project or operating a data center with tons of server racks, hypervisors create a gateway to convenience, efficiency, and scalability.

And trust me, if your business has multiple physical servers (or even a single server, really), you absolutely need to step into the world of hypervisors — running separate servers for applications or services is, well… the headless chicken approach.

Getting started with hypervisors is easier than you think, don’t worry! For now, let’s look at their benefits.

Resource Efficiency

Talking about headless chickens… gosh. The image is ingrained in my head.

Getting back to the point, in many cultures, people cook and eat almost every part of a chicken.

Yes, even the feet and brain. Anyway, your goal should be to maximize hardware utilization — thereby reducing waste.

So instead of dedicating an entire physical machine to a single workload, use a hypervisor to run multiple VMs on the machine. No resources should go to waste.

Flexibility and Portability

Migrating physical servers is strenuous and transferring data is your biggest challenge.

With VMs, you can easily move an entire system (operating system, data, and applications) as a single file, with almost zero downtime! Talk about convenience.

So whether you’re moving to a bigger server, performing repairs or maintenance, or migrating to the cloud, VMs travel light (unlike my girlfriend) and can go wherever you need them.

Isolation

You can think of VMs as secure “bubbles” within your system. If one of these bubbles “burst”, others won’t be compromised.

Since VMs are isolated from each other and the host system, they enhance security and reduce risk.

To put it into perspective, if you want to test software or run an untrusted application, you can create a VM for it without fear of it affecting the rest of your environment. Virtual machines are badass, I know.

Scalability

Just as an infant needs milk for nourishment, your business needs resources to scale up and meet demand.

Now, there are two ways you can achieve this: by purchasing more hardware or spinning up more virtual machines.

If you have sufficient resources to spare, always choose the latter. After all, hypervisors are all about growth.

If you have a brilliant idea, and you’re itching to test it, create a VM and quickly deploy the new environment. Who knows, you may have a million-dollar baby in the making!

Cost Savings

It goes without saying that virtual machines reduce physical hardware needs and energy consumption.

If your accountant isn’t familiar with the concept of virtualization, can you imagine the joy in their eyes (replace their pupils with dollar signs, like in the cartoons) when you show them the cost savings you can achieve through virtual machines?

VMs are more efficient, greener, and cheaper — what’s not to love?

Plus, the money you save using virtual machines can be reinvested into your business or saved for a rainy day. The world is your oyster!

My brother works in aviation, so I take a keen interest in the industry. You don’t have to be a pilot to understand the importance of air traffic control towers, especially at a busy airport like the Hartsfield-Jackson Atlanta International Airport (the world’s busiest airport).

You can compare hypervisors to them in modern IT infrastructure — they allow your applications to “take off” and “land” without clashing with each other. But you already knew that!

All good things come at a cost, and I’m not just talking about the licensing costs of hypervisors here (it sure is a point of contention!). You’re bound to face some challenges while using hypervisors, and of course, it has its limitations.

That’s why some people prefer containerization. Here are some of the challenges and limitations of hypervisors. I hope you can take them in stride and make the best of the technology!

Performance Overhead

Let me put it simply for you: when you hire a middleman to do a job, they take a cut. And while the cut may not burn a hole in your pocket, it’s significant, especially when the middleman is a hypervisor.

So while a hypervisor does a fine job of allocating resources to VMs, it’s software in the end — it needs resources to function. In a nutshell, you might have to trade off some performance for the flexibility and scalability that comes with virtualization.

Complexity

If you thought configuring and managing virtual machines through hypervisors is as easy as making scrambled eggs, boy, are you mistaken. You need specialized expertise, as misconfigurations can lead to inefficiencies or system failures.

Virtual machines have inherent complexity in their setup and management, but it’s nothing you can’t overcome with a skilled expert.

The good news is, if you’re familiar with basic IT concepts like operating systems, computer hardware, and networking, there are tons of free online resources you can explore to master the dark arts of virtualization. And do get your hands dirty — the best way to learn is by doing.

Security Risks

While VMs are isolated from one another, they do have a potential weak link — the hypervisor layer. Vulnerabilities in the hypervisor layer could affect not only VMs but the host machine.

While hypervisors are designed with security in mind, just like any other complex software they’re not immune to vulnerabilities. You should do your bit by keeping the hypervisor software updated and securely configuring it.

Licensing Costs

If you want to experiment with hypervisor technology, there are several open-source options (such as Kernel-based Virtual Machine (KVM) and Xen) on the market.

And while they can be successfully used for enterprise workloads, you need to have the right expertise to deploy, manage, and scale these platforms effectively.

Proprietary hypervisors are generally a much better option but may involve significant expenses, especially when you scale your infrastructure.

Here’s more on the enterprise-grade and open-source hypervisors you should take a look at.

Enterprise-Grade Hypervisors

VMware and Microsoft are giants in enterprise virtualization. The solutions they offer come with polished enterprise features out of the box and advanced support.

So, if your budget is on the higher side, and you want the best possible virtualization features at hand, consider these hypervisors:

• VMware ESXi: ESXi is a leader in enterprise virtualization and according to me, its capabilities are unmatched. If you’re looking for a virtualization solution to manage your complex IT environments, you have a winner in ESXi.
• Microsoft Hyper-V: On the other hand, Hyper-V integrates with Windows Server, which makes it a fascinating choice for Microsoft enthusiasts. Of course, it’s not limited to Windows VMs — it provides a solid set of tools to manage Linux VMs as well.

You’re looking at estimated monthly costs of between $250 to $1,800 for three hosts, so do your research thoroughly and set aside a significant budget!

Open-Source Solutions

If you don’t have an average monthly budget of around $1,000 to spend on hypervisor software, there are several open-source solutions on the market.

While they don’t have the finesse of a Roger Federer, they’re as much a winning machine as Novak Djokovic. Of course, you’ll have to work harder.

• KVM: Kernel-based Virtual Machine is widely used in Linux environments and should be a natural fit for you if you’re already running Linux servers.
• Xen: Xen is known for its high performance and supports several guest operating systems. It has a long history in enterprise and cloud platforms and yes, you can use it for large-scale deployments.

If you just want something for testing or personal use, I have the perfect solution for you. Read on.

Developer Tools

VirtualBox is a free, easy-to-use hypervisor for individual use. So if you’re just getting the hang of virtualization or want a tool for testing out different OSes, VirtualBox is a fantastic option.

Don’t mistake the hassle-free experience it offers for a lack of “oomph.” While it may not be at the level of Federer or Djokovic, it offers numerous features that are perfect for individual users or small-scale projects. You could use it to win a Grand Slam, or two.

There’s no such thing as the “perfect fit”. When you’re shopping for sneakers online, for instance, if you select a particular size in your filters, you might find a slight variation in the same size across brands. Perfection is a myth.

However, by taking note of these key considerations, you can find the best possible hypervisor for your needs. By the way, I do have a solution for your sneaker conundrum — the thickness of your socks can make a world of difference!

Key Factors to Consider:

• Performance requirements: Some people have a greater appetite than others. If your applications are less demanding, you can probably get by with a lightweight hypervisor. On the other hand, if you’re running resource-hungry apps, you need a heavyweight hypervisor that can handle the heavy lifting without slowing things down.
• Workload type (enterprise, development, testing): This one’s pretty simple. You need to figure out whether you need to create virtual machines to run enterprise-grade apps, set up development environments, or just test some code. Enterprise environments, for example, may need greater scalability and security while development and testing environments may require more flexibility and ease of use.
• Budget and licensing: Money talks. The higher the price tag associated with a hypervisor, the more features are at your disposal. Free hypervisors do pack a punch, though, so a low budget doesn’t entirely rule you out of contention for a spot in the world of virtualization.

With these recommendations, you should be able to figure out whether you need a Type-1 or Type-2 hypervisor. Here comes the fun part: actually choosing one. For personal use, VMware Workstation Pro is a favorite of mine, and yes, it’s free, free, free! Small businesses should look at either VMware ESXi or Microsoft Hyper-V.

They’re affordable yet powerful hypervisor solutions. Large businesses can’t go wrong with either VMware vSphere or Microsoft Hyper-V Server.

Virtualization is like a superpower, and I know for a fact I’ve set into motion the first steps you need to unleash it.

While most businesses favor cloud-based solutions or third-party managed services, a hybrid IT approach is preferred — especially if your business deals with sensitive data. In such cases, physical servers are ideal for enhanced data security and compliance requirements.

Through hypervisors, you can create virtual machines to manage these workloads and introduce an additional layer of security. You can also easily migrate these workloads from your physical servers to the cloud through virtual machines.

It’s a win-win, really. With virtual machines, you can truly enjoy the flexibility and scalability of the cloud and the control and security of in-house servers.

Speaking of superheroes, “The Hypervisor” would be a pretty neat name. The Hypervisor — the true commander of the virtual worlds!