Disk erase Failed:

Discussion in 'MacBook Pro' started by MacKid1983, Dec 30, 2011.

  1. MacKid1983 macrumors 6502


    Oct 1, 2011
    I have a MBP and trying to erase my HDD and I get an error "Disk Erase Failed' Could not unmount disk.

    I have lion. Any Suggestions? I want to sell my Mac.
  2. iThinkergoiMac macrumors 68030

    Jan 20, 2010
    Have you booted from the install disc? You cannot erase the disk you are currently running the OS from.
  3. thebritishguy macrumors member

    Dec 30, 2011
    Make sure spotlight is not indexing, i recently had exactly the same issue when i installed a second drive, you should also restart finder using Alt, command, esc
  4. simsaladimbamba

    Nov 28, 2010


    Links to guides on how to use Disk Utility, the application Mac OS X provides for managing internal and external HDD/SSDs and its formats.

    What does that have to do with the OP's question?
    Ah, I see, that that is your first post.
  5. MacKid1983, Dec 30, 2011
    Last edited: Dec 30, 2011

    MacKid1983 thread starter macrumors 6502


    Oct 1, 2011
    I *think* i booted from the flash drive.....

    I have a flash drive with a Lion on it, Installed lion and copied the "install.dmg" and I want to erase my hdd with a few passes and re-install lion.

    I started my computer while holding down "COMMAND R" and opened disk utility and wanted to erase the hdd that way.

    But I just read on a site to do this: "Restart your computer by holding down the option key. You will now be given an option to boot from the DVD or USB drive. Go through the installation, ready to enjoy a new, clean install of Lion."

    Am I restarting the incorrect way? But before I re-install lion I want to erase the HDD"

    I read some of the articles simsaladimbamba posted but I dont quite get what "To format, erase, or reformat your Startup volume (the OSX volume on your internal HD), you must start your Mac up from a different source: •On Lion, the Recovery HD or OSX USB thumb drive."

    Thats what I am doing, by restarting my Mac while holding down "COMMAND R". Or do I just hold down
  6. Mal macrumors 603


    Jan 6, 2002
    Your flash drive is being completely ignored if you're holding down Command R on restart, because that boots from the recovery partition (or internet recovery if you have a model that doesn't have the recovery partition). Hold option to boot from the flash drive, assuming you set it up correctly, and you can use Disk Utility from there to erase your hard drive.


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