S'il vous est impossible de démonter un disque (macOS)

Vous pouvez essayer de démarrer le mode Récupération (en pressant 'CMD + R' au démarrage du mac).

You can try booting from OS X recovery by holding CMD + R at the time of startup. Once booted from OS X recovery, select Terminal from the utilities and then at the unix prompt enter:

- diskutil list - then press return and look for the disk identifier and enter the following command with the disk identifier: -

sudo diskutil unmountDisk /dev/(enter here disk identifier name)

- Press return and enter your admin password if prompted. This should unmount all volumes of the physical drive. - If still the above method didn't work, then the last option is to force the entire disk to unmount. - For that using the terminal application again, enter the following command:

sudo diskutil unmount force /dev/(enter here disk identifier name)

- Then press return and enter the admin password if prompted. This will definetely unmount the entire disk and all its related volume.