> ## Documentation Index
> Fetch the complete documentation index at: https://docs.mountthor.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Compute types

> Bare metal or a virtual machine: what each gives you and when to use it

Mount Thor runs two kinds of machine on Apple Silicon Macs. The biggest
difference is what you may change on the machine.

| | Bare metal | Virtual machine |
| - | - | - |
| What you get | One physical Mac, used only by you | An isolated macOS VM on a Mac reserved for you |
| Hardware | The whole Mac | One of two VM slots on the Mac; the other slot is yours too |
| Your account on it | A permissive, non-root user | An administrator, with `sudo` |
| Change system settings | No | Yes |
| macOS | The version installed on the Mac | The image you choose |
| Charged | Per Mac, in 24-hour windows | Per Mac, which holds two VMs |

## Use a virtual machine when you need administrator rights

You sign in to a VM as an administrator and can run commands with `sudo`. Use
a VM when a workload changes the system itself: system settings, launch
daemons, or kernel and network configuration.

A VM is also the right choice for parallel jobs and fast create-delete cycles.
See [Virtual machines](https://docs.mountthor.com/compute/virtual-machines.md).

## Use bare metal for dedicated hardware

A bare-metal Mac is yours alone for the length of the lease. Use it when a
workload needs a whole physical Mac, such as performance measurement that must
not share hardware, or software that will not run inside a virtual machine.

The account you sign in with on a bare-metal Mac is a permissive, non-root
user: it runs your tools and workloads, but it is not an administrator and
cannot change system settings. If you need administrator rights, use a
virtual machine instead. The [Bare metal](https://docs.mountthor.com/compute/bare-metal.md) page covers
allocation, access and release.

## Machine classes

You create both types as a class of machine, such as `m4-24g`. The class
specifies the Mac hardware allocated to you. List the classes available to
your account with the API's machine classes endpoint,
`GET /compute/v1/catalog/machineclasses`, select one in the portal, or pick
one interactively with `mthr vm create` and `mthr bm allocate`.


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