Zero Out Delete Mountain Lion Problem

Discussion in 'Mac Basics and Help' started by vaxes, Dec 30, 2012.

  1. vaxes, Dec 30, 2012
    Last edited: Dec 30, 2012

    macrumors newbie

    Sep 21, 2012

    I'm selling my old iMac (2 months old) which I used for work so I want to do a 7 pass zero delete.

    I've created a boot disk on usb stick and can boot up from it using either cmd+r or option but when i try to erase the HD i get the warning

    "Secure Disk Erase Failed"
    "Couldn't unmount disk"

    I've looked every where and can't see where im going wrong even apple care isnt open on a sunday.

    Thanks in advance for any help

    *Dont worry I fixed the problem*
  2. macrumors G5


    Jul 29, 2011
    Somewhere Back In The Long Ago
    I guess you are trying this with the stick in? Take it out, hold OPTION on boot, enter Disk Utility and perform the erase. Then boot with the stick in the drive, but you would only need to install the version of OSX that came with your Mac originally.
  3. macrumors 6502a


    Jul 24, 2011
    United States
    Are you sure that it is indeed booting from the USB drive instead of the Recovery HD 10.8.2?

    Try holding down CMD+Option+R at the same time and doing an Internet Recovery. This will download the baseimage.dmg file from Apple's servers, therefore no files will be in use on your local hard disk. It will take a few moments to boot, but after it does you can wipe the entire disk, do a secure erase, and reinstall 10.8.2.

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