Lion: Reformat SSD - couldn't unmount disk?

Discussion in 'MacBook Pro' started by lhan16, Mar 14, 2012.

  1. lhan16 macrumors newbie

    Jan 23, 2012

    I have been searching for a solution to this but finally decided to post my question. I've come across several threads about the error message "couldn't unmount disk" from the Disk Utility but every "solution" I've tried gives me the same message.

    So long story short, I have a late 2011 MBP that I've had for a couple months. I have (had) windows 7 running on bootcamp on a partitioned SSD that I put in. A few days ago some updates failed and my computer wouldn't even turn on so I reinstalled Lion via Internet Recovery (which is awesome btw).

    I decided that I want to do away with the Windows 7 Partition and just go back to how it was when i got the computer and completely reformat my SSD and re-install Lion using only ONE partition.

    After several unsuccessful attempts I can not get this done. I created a bootable USB recovery drive with the Lion Recovery Assistant and am trying a restart + holding the option key so I can boot from it.

    Once I boot from the recovery drive I thought I was supposed to be able to erase both of my partitions and change the partitioning on my SSD to 1 partition. EVERY TIME I try it I get the "couldn't unmount disk" error. I really have no idea what to try next or what I can even do. I've tried "verifying" and "repairing" both of the partitions, directly mounting and unmounting, etc, with no luck.

    Can anyone tell me how to just wipe both partitions from my SSD with the Disk Utility and start fresh?

    Many thanks in advance!!!

  2. dusk007 macrumors 68040


    Dec 5, 2009
    DiskUtility doesn't seem to be the most fault resistant program.
    Have you tried booting from a Linus or Windows startup disk.
    At least the formatting part they should do just fine.
  3. lhan16 thread starter macrumors newbie

    Jan 23, 2012
    You mean booting from windows and then reformatting my SSD from there? would I need to make a bootable disk or USB drive to do that? If so, why couldn't I just do that when booting from my Lion Recovery USB drive?

    Another thought is, can I re-install Lion on one of the partitions and then when I boot into that partition, can I remove the other partition? or combine them?

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