Can't unmount disk problem?

Discussion in 'MacBook Pro' started by UsuallyWindows, Jan 12, 2017.

  1. UsuallyWindows macrumors newbie

    Jan 12, 2017
    I am trying to erase my Macintosh HD but I keep getting a error saying I can't unmount the disk. I am booting up from the install CD so IDK what the problem is
  2. BrianBaughn macrumors 603


    Feb 13, 2011
    Baltimore, Maryland
    Sometimes it indicates that there's some process using the disk...which is odd but happens.

    Search for how to use Terminal to force unmount a disk.
  3. ihatetoregister Suspended


    Sep 13, 2016
    Oslo, Norway
    Exactly what BrianBaughn says : Check if you have a program still accessing it (anything from finder to 3rd party program to Time Machine encrypting your disk etc).
    In activity monitor you can force close a program that can't be stopped FYI.

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