Erasing Hard Drive

Discussion in 'MacBook' started by ftbtef, Sep 2, 2011.

  1. ftbtef, Sep 2, 2011
    Last edited: Sep 2, 2011

    ftbtef macrumors newbie

    May 29, 2011
    Hi, I recently inherited a 2007 MBP 15-inch. I erased the hard drive, reinstalled SL, updated to 10.6.8, and installed Lion. It is all set up now, and surfing the web I learned that it is recommended to use the security options when erasing the HD. I didn't even see them. I assume that it didn't use any security measures.

    Does this mean I will have less space on my HD than if I had used the security options? And if so, I have another question. I don't want to go through the huge SL/update/download Lion/install Lion/transfer-files rigamarole again.

    Would it be possible to erase the hard drive again, this time using the security measures, then use Time Machine from Snow Leopard to restore the MBP and my files to the way it is right now? Or would this just end up restoring the old data I don't want (from the previous user) back to my computer?

    Thanks for any help, sorry this is so long.
  2. treestar macrumors 6502

    Feb 28, 2010
    You are fine. Don't do anything.

    Secure Erase is a method of erasing to prevent any data from being recovered. It does not affect capacity. It's possible if you tried very hard you could recover some of the files that were on the HDD before it was given to you. That's all. You will overwrite them eventually.
  3. ftbtef thread starter macrumors newbie

    May 29, 2011
  4. DewGuy1999 macrumors 68040


    Jan 25, 2009
    If you're concerned about what was on there previously, you could always use the Erase Free Space... option in Disk Utility. Here's the info from Snow Leopard's Help (I imagine it's the same for Lion) on what it does and how to use it:

    Erasing free disk space
    When you delete files by emptying the Trash, Mac OS X deletes the information used to access the files but doesn’t actually delete the files. Although the disk space used by deleted files is marked as free space, deleted files remain intact until new data is written over them. As a result, deleted files can be recovered.

    You can use Disk Utility to erase the free space used by deleted files by having zeros written over the space once, 7 times, or 35 times. If you have a lot of free space on your disk, overwriting the free space several times can take a long time.

    Erasing free disk space does not erase the other files on your disk.

    To erase free disk space:

    1. In Disk Utility, select the disk or partition in the list at the left with the free space you want to erase.
    2. Click Erase, and then click the Erase Free Space button.
    3. Select how to erase the free space, and then click Erase.
    After the process begins, you can interrupt it without harming your data.

    You might see a message that says you are running out of disk space, but you can ignore that warning. When this operation is complete, you will have the same amount of free space as you did when it started.

    You can also erase free space when you empty the Trash in the Finder. Choose Finder > Secure Empty Trash.​

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