Type 1 vs Type 2 Hypervisors: What’s the Difference?

Type 1 (bare metal) and Type 2 (hosted) hypervisors are two different ways of running virtual machines (VMs). Understanding their differences can help you choose the right one for your needs.

What is a Hypervisor?

A hypervisor, also known as a virtual machine monitor (VMM), is software that allows multiple operating systems to run on a single physical computer. Each VM runs its own operating system and believes it has exclusive access to the hardware resources. The hypervisor manages the allocation of CPU, RAM, and storage between these VMs.

Type 1 Hypervisors

Type 1 hypervisors are also known as "bare metal" because they run directly on the host computer's hardware without an underlying operating system. This means that the hypervisor itself acts as the primary OS.

Examples: Proxmox VE, VMware ESXi, Microsoft Hyper-V (server role), XCP-ng, KVM (built into Linux).
Use Cases:
- Servers and Homelab Servers: These are typically used in server environments where minimal overhead is crucial. Type 1 hypervisors provide near-native performance for VMs and can run continuously without the need to reboot.
- 24/7 Unattended Operation: Ideal for hosting services, development servers, or any environment that requires constant uptime.

Type 2 Hypervisors

Type 2 hypervisors are hosted on top of a traditional operating system. They require an additional layer of software and thus have more overhead compared to type 1 hypervisors.

Examples: VirtualBox, VMware Workstation/Fusion, Parallels.
Use Cases:
- Convenience and Testing: Useful for testing new operating systems or running VMs on a desktop computer. These are often free or inexpensive and can be easily installed and uninstalled.
- Trial and Development: Great for experimenting with different environments without the need to set up a dedicated server.

Blurry Line Honesty

Modern virtualization technologies leverage hardware features like Intel VT-x and AMD-V, which reduce the performance gap between type 1 and type 2 hypervisors. The differences are more pronounced in disk I/O and network paths. Additionally, Windows Subsystem for Linux (WSL2) and Hyper-V on Windows blur these distinctions further.

Which One Do You Want?

For Learning or Testing on Your Daily Machine: Use a Type 2 hypervisor like VirtualBox.
For a Homelab Server Always On Hosting Services: Opt for a type 1 hypervisor like Proxmox VE, especially in environments where VMs need to survive host reboots.

Containers (Docker): Share the host kernel instead of virtualizing hardware. They are lighter but less isolated.
Snapshots: Save the state of a VM to roll back to later if needed.
Live Migration: Move a running VM between hosts, typically in type 1 clusters for high availability and load balancing.

By understanding these differences, you can make an informed decision about which hypervisor best suits your needs.