Disk Utility Help Needed.

Discussion in 'macOS' started by ShadowedSight, Aug 23, 2011.

  1. ShadowedSight macrumors newbie

    Apr 29, 2011
    Okay guys, I really need some help.
    I bought a Macbook Pro with Lion installed. I setup Windows with Bootcamp and ran that for a while. Now, I wanted to clean install JUST Macosx for school in two days. I deleted the Bootcamp partition with Disk Utility, like an idiot. I made a Lion Recovery External Drive and I'm trying to just erase the entire hard drive. Whenever I go to do that though, it says "Unable to unmount." I'm really stuck, and I could use some help. All I want to do is delete everything off this hard drive and start again.

    Please help, anyone. And thank you so much!
  2. unixperience macrumors regular

    Jul 21, 2010
    hey mate, its actually pretty simple..... well unless they changed things with lion... everything that should be simple isn't... but anyway

    you typically can't unmount the os, and you can never delete a mounted partition... because you are using it. there are two ways around this, one is to use an osx install cd, then use the disk utility from there, because you are running off the CD, NOT the hd.

    If you have a bootable backup, you can also boot from the backup, and use the disk utility again on the internal drive.
  3. gr8tfly macrumors 603


    Oct 29, 2006
    ~119W 34N
    So you are booted off of an external USB stick with the Lion Recovery HD on it or Lion Installer? You will need to startup using this - not the internal drive.

    I'm not sure exactly why you would get the error (unless, as the previous post said, you are booted off the internal drive), but if you want to erase the entire drive, you can set it up with a single new partition. In Disk Utility, select the drive itself (not a partition), then click on the Partiton tab. In the layout menu, select "1 Partition", format "Mac OS Extended (journaled)". Then, click Apply. This will erase all the data on the drive.

    Is your USB drive just the Recovery HD partiton, or is it a full install? If the former, you will be downloading Lion, so expect the install to take a bit of time.

    I'm not clear on how you recover iLife, but either it will be part of the recovery install, or you will be able to download it from the Mac App Store. I just haven't read of exactly what the procedure for that is.
  4. Quad5Ny macrumors 6502a


    Sep 13, 2009
    New York, USA
    If you have your reinstall media, then I'm guessing the steps below are what your looking for?


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