You can tell if it's the same drive with disk XsY (Y is just to say what partition it is) This means that MountEFI may report multiple drives in it's picker but each partition will still share the same EFI(The UEFI spec only allows for 1 EFI per drive). With macOS Catalina, macOS is actually partitioned into 2 volumes: System Partition and User Partition. Now with this done, lets mount our macOS drive. Note: Installers made with gibMacOS's MakeInstall.bat on Windows will default to a Master Boot Record(MBR) partition map, this means there is no dedicated EFI partition instead being the BOOT partition that mounts by default in macOS.

We'll then want to eject the USB drive's EFI as having multiple EFI's mounted can confuse macOS sometimes, best practice is to keep only 1 EFI mounted at a time(you can eject just the EFI, the drive itself doesn't need to be removed) Once the EFI's mounted, we'll want to grab our EFI folder on there and keep in a safe place. To do this, we'll be using a neat tool from CorpNewt called MountEFI (opens new window)įor this example, we'll assume your USB is called Install macOS Catalina: So to start, we'll first want to grab OpenCore off of our installer. # Moving OpenCore from USB to macOS Drive # Grabbing OpenCore off the USB