I just plugged in my external hd via USB for a Time Machine backup. However it will not mount.

enter image description here


  • Unplugged the hd
  • Restarted the computer
  • Plugged it back in

When I do this, Disk Utility spins and won't load. So I then:

  • Unplug the disk
  • Open Disk Utility
  • Plug in the disk and that shows the image above

When I press mount, it says the disk is already unlocked. However it will not show up.

This started after I tried repairing the volume, but it wouldn't repair. Now I can't select it.

Any options at this point other than erasing the whole HD and starting over?


I've had problems like this also. If you have multiple USB ports try using a different port. Also try using a different cable and a different port.

You don't want to use a flaky drive for your backup. So, yes it seems like reformatting the drive and starting over makes sense, or replace it.

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The drive repair function in Disk Utility is and always has been mostly useless. If you really want to repair a drive (with software problems, not hardware problems of course), you need a program like Disk Warrior.

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