6 Replies Latest reply: Jan 21, 2013 11:53 AM by dk10438
dk10438 Level 1 Level 1 (0 points)


I recently purchased a Mac Mini with the fusion drive.  When I perform a verify and repair of the disk, I get the error "The disk Macintosh HD could not be unmounted".  This does not occur with any of my other computers, imac or powermac (also running mountain lion).  So I am wondering if I have a defective Fusion/HD or if this is simply a peculiarity of the fusion drive itself.  Please comment.

Mac mini, OS X Mountain Lion (10.8.2)
  • BDAqua Level 10 Level 10 (119,365 points)



    Were you doing this from the Restore Partition? I ask because the SSD & HDD are seen as one drive normally.


    Bootup holding CMD+r, or the Option/alt key to boot from the Restore partition & use Disk Utility from there to Repair the Disk, then Repair Permissions.

  • dk10438 Level 1 Level 1 (0 points)

    when I boot from the restore partition, there is no error.  However, when I spoke to apple, they said that the disk is already unmounted.  when I boot up normally and run the disk utility, i get


    Verify and Repair volume "Macintosh HD"

    The disk "Macintosh HD" could not be unmounted

  • BDAqua Level 10 Level 10 (119,365 points)

    Hmmm, no SSD or Fusion here, but DU Veries the Boot Drive whilst booted from the same drive here.


    I wonder if Spotlight Or TM has it in use?

  • VikingOSX Level 6 Level 6 (9,335 points)

    If your Fusion drive can be repaired with Disk Utility, it will be shown with red lettering. If you are not seeing red lettering, then you need to boot into Recovery mode to use that Disk Utility. When you order a Fusion drive equipped Mac, there is a special version of Disk Utility included in OS X specifically for operation with Fusion Drives.


    If you have any open files on the volume you wish to verify/repair, then Disk Utility will throw its hands up and give you that cannot unmount drive message. Make sure you have quit all applications you were using that may be accessing files on the disk in question.


    Apple article.

  • RRFS Level 5 Level 5 (4,490 points)

    You should try Internet Recovery Disk Utility. "Command + Option + R" on reboot.

  • dk10438 Level 1 Level 1 (0 points)

    I've tried the internet recovery disk utility (command + option + R) and I don't get errors.  However, when I boot off of the drive, I continue to get errors.  I think that there is something wrong with the drive itself since I am unable to have a successful time machine backup (which led to identification of the problem to begin with).  I know the hard drive that I am trying to back up with works since I have performed a back up on another one of my macs.  Unfortunately, I have not been able to backup the mini with the fusion drive, despite reinstalling mountain lion on numerous occasions, repartitioning, disk repairing, etc.