Boot from USB flash drive in VirtualBox MacOS

Imagine you have a bootable flash drive and you want to test it (try to boot from it). For example, we will boot from Windows 11 bootable USB flash drive. I will show you how to do this under MacOS using VirtualBox.

Step 0: plug in USB drive

We need a /dev/disk<number> file related to our drive. But MacOS will also automatically mount any USB drive to /Volumes/ folder. We don't want that. The USB drive shouldn't be mounted. You could eject the drive in Finder but it also deletes the /dev/disk<number> file. Thus we need some third-party app that prevents USB drives from mounting. We will use an open-source app called Disk Arbitrator (Github). We open the app and plug-in our drive: Disk Arbitrator app screenshot

On this screenshot we see the mode ("Block mounts") and the dev file (/dev/disk<number>).

Step 1: create VMDK linked to /dev/disk<number>

VirtualBox doesn't provide the ability to use a USB drive explicitly for booting. Instead, we will create a VMDK image which will be linked to the dev file of our USB drive /dev/disk<number>:


          sudo VBoxManage internalcommands createrawvmdk -filename ./usb.vmdk -rawdisk /dev/disk<number>

And this is very important:


          sudo chmod 777 ./usb.vmdk
          sudo chmod 777 /dev/disk2

Step 2: Create a virtual machine

Now we need to create a virtual machine and use this VMDK image:

Create a virtual machine interface screenshot

Start our virtual machine: virtual machine started