#MAC CANNOT UNMOUNT DISK TO ERASE MAC OS#

Note : You will need an active Internet connection. Reinstall Lion/Mountain Lion, Mavericks : Select Reinstall Lion/Mountain Lion, Mavericks and click on the Install button. The Erase button and wait until the process has completed.

The Security button and set the ZeroData option to one-pass.

#MAC CANNOT UNMOUNT DISK TO ERASE MAC OS#

Set the format type to Mac OS Extended (Journaled.) Optionally, click on Click on the Erase tab in the DU main window.ģ. After DU loads select your startup volume (usually Macintosh HD) from the Select Disk Utility from the main menu and click on the Continue button.Ģ. Install or Reinstall Mavericks, Lion/Mountain Lion from Scratchīe sure you backup your files to an external drive or second internal drive because the following procedure will remove everything from the hard drive.ġ. If Couldnt Unmount Disk or erase process has failed error occurs, the simplest solution is to boot the Mac system and run Disk Utility on the disk. This should unmount the drive so you can now do this: For a single drive system this will probably be /dev/disk0. You should also see the name of the disk such as 'Macintosh HD.' Note down the disk identifier. If will look like /dev/diskn/ where 'n' is an integer starting at 0. From the listing look on the left column for your disk identifier. If you are, then you neeed to do the following: Are you booted from the Recovery HD partition? If not, then you need to first boot from the Recovery HD before you can erase the Macintosh HD.

Mac cannot unmount disk to erase