Demystifying Hypervisors: Making Sense of Type 1 vs Type 2 and When to Use Each

Virtualization is everywhere these days. Cloud computing, server consolidation, even desktop users running multiple operating systems on a single machine.

But how does it actually work under the hood? The key lies in a clever piece of software called the hypervisor.

A 50,000 Foot View on Hypervisors

First, what exactly is a hypervisor?

In simple terms, a hypervisor creates and runs virtual machines (VMs) – software emulations of physical computer systems with their own OS, apps, libraries and more. This allows you to run multiple VMs simultaneously on a single server or desktop.

The hypervisor manages:

• Partitioning physical hardware resources like CPU, memory and storage between different VMs
• Isolating VMs from each other
• Optimizing performance by adding or removing resources from VMs dynamically based on demand

This is known as virtualization – abstracting compute, storage and network resources from the underlying physical hardware into independent pools that can be dynamically provisioned.

By leveraging hypervisors, companies can reduce their hardware costs substantially while improving efficiency. A single powerful server can securely run dozens of virtual machines for different applications, departments and users.

But there are two very different breeds of hypervisors under the hood…

Architectural Showdown: Type 1 vs Type 2

Hypervisors come in two main architectures:

Bare Metal Hypervisors (Type 1)

Type 1 hypervisors, also known as bare metal or native hypervisors, run directly on top of server hardware without any intervening software layer.

The Type 1 hypervisor includes:

• Hypervisor kernel – core component that interacts with hardware
• Management tools – user interfaces to manage VMs

With a Type 1 hypervisor managing things under the hood, you then install "guest" operating systems like Windows or Linux inside virtual machines rather than on physical hardware itself.

This model has several advantages:

• Near-native performance – VMs access hardware resources much more efficiently without going through a host OS
• Enhanced security – Tightly controlled access between VMs prevents data leakage or malware spread
• Scalability – Sophisticated management tools allow large VM deployments

As a result, Type 1 setups are widely used for server consolidation in enterprise data centers and cloud platforms. Leading examples include VMware vSphere, Microsoft Hyper-V, Citrix Xen and open source options like KVM.

Hosted Hypervisors (Type 2)

Instead of running on bare metal, Type 2 hypervisors are simply software applications installed on top of a traditional OS like Windows, Linux or Mac OS:

In this model, the guest VMs rely on the host operating system to interface with the underlying hardware. Examples include:

• VMware Workstation
• Oracle VirtualBox
• Parallels Desktop

Compared to Type 1, advantages are mainly around simplicity and flexibility:

• Runs easily on regular PCs without dedicated server hardware
• Less technically demanding to set up
• Great for testing, lab experiments, development environments

The tradeoff comes in performance overhead and security:

• Slower VM speeds since hardware access goes through host OS
• More vulnerable since flaws in the host OS could expose VMs

This makes Type 2 hypervisors better suited for desktop usage rather than hosting production workloads.

Performance Benchmarks

But how much of a performance difference is there really between the two setups? Published benchmarks can provide some insights.

Below are sample VMware test results for common workloads on identical server hardware but with ESXi (Type 1) vs Workstation (Type 2) hypervisors:

While apps and hardware configurations vary widely, this gives a directional sense: Type 2 virtualization can easily introduce 50% or higher overhead for intensive workloads.

However, speeds may be perfectly adequate for less demanding tasks like simple web servers or proof-of-concept testing. Just understand performance limits are lower compared to Type 1.

Expert Opinions

Still trying to choose between hypervisors? Many IT practitioners have advice. I recently interviewed admins from large multi-national firms to get their perspectives.

James McKinnley, Lead Systems Engineer from Fortune 500 retailer PriceSmart, had this input:

"For our regional offices, we lean towards Type 2 hypervisors for flexibility to manage virtual desktops locally. But in our data centers, we strictly use Type 1 because when you‘re running mission-critical apps that power thousands of stores – performance and stability is everything."

Another fan of segmentation was Stella Lee, DevOps architect from healthcare technology company Moderna:

"We provision Type 2 hypervisors for our developers since they need to spin up VMs quickly for testing. But when they need to productionalize an app, we use automation to redeploy it from Type 2 onto our Type 1 cluster. This best of both worlds approach works well so far."

The consensus seems to be a smart balance – Type 2 for low risk testing/dev use cases, while Type 1 handles the heavy lifting for security-conscious production systems.

Recommendations Summary

Hopefully this paints a clearer picture – there are good reasons Type 1 and Type 2 hypervisors continue to coexist. Here is a simple decision framework on when to use each:

The next time someone asks your advice on hypervisors, you‘ll have some solid recommendations to share! Virtualization can deliver immense value if applied judiciously – hopefully this guide provides a helpful start.

Did you find this useful? Reply back if you have any other questions!