ELi5: What does the term “bare metal” refer to when it comes to virtual machines? To me, it just sounds like having two different operating systems on the same computer that you can switch between on the boot screen.

Question

Someone PLEASE explain to me what bare metal is and why I keep hearing about bare metal hypervisors.

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Answer 1

Bare metal means the system is **not** a virtual machine. A bare metal OS is a “real” operating system running directly on the hardware. However, a bare metal system does not need to be a “normal” operating system like Windows that you use for day to day tasks, it can be specialized for the purpose of running other OSes as virtual machines. That’s a hypervisor. Hyper-V for example is the “primary” operating system that runs on your hardware, so it is a bare metal system. However you wouldn’t use Hyper-V to browse the web or play games or do office work. You’d only use it to run Windows, Linux, etc as virtual machines.

A hypervisor does not need to be bare metal. For example VirtualBox lets you run virtual machines. But VirtualBox is an application you might run within Windows. It is not the primary operating system of the computer. A bare metal hypervisor will offer better performance for the virtual machines compared to running an OS within an application within another OS.