pjttty
Level 1 (4 points)
Notebooks

Q: Does 7-pass secure erase wipe the entire drive (including unused disk space)?

I'm selling my old macbook and I need to do a secure erase; I've used internet banking on there before and I've also stored customer's private information as part of my job (nothing more than names and phone numbers, but still).

 

Does 7-pass secure erase (as part of the disk utility) secure erase the entire drive, including files that have already been deleted the normal way? Or does it only secure erase the files still available?

 

Also, I'm aware that 7-pass is overkill but I'd rather do it for peace of mind.

 

Thank you!

MacBook Pro, OS X El Capitan (10.11.5)

Posted on Jun 19, 2016 4:31 AM

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pjttty

Q: Does 7-pass secure erase wipe the entire drive (including unused disk space)?

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  • Helpful answers

  • by OGELTHORPE,

    OGELTHORPE OGELTHORPE Jun 19, 2016 4:36 AM in response to pjttty
    Level 9 (52,521 points)
    Mac OS X
    Jun 19, 2016 4:36 AM in response to pjttty

    Yes it will do the entire HDD.  It would seem simpler to replace the HDD with a new one, then you would not have to concern yourself with the lengthy delete process.

     

    Ciao.

  • by Grant Bennet-Alder,

    Grant Bennet-Alder Grant Bennet-Alder Jun 19, 2016 7:30 AM in response to pjttty
    Level 9 (61,083 points)
    Desktops
    Jun 19, 2016 7:30 AM in response to pjttty

    For magnetic rotating drives:

     

    Quick (default) erase simply writes over the directory area on the drive. It does not erase the data blocks of files. Common Utilities like Norton Disk Doctor can "un-erase" some files.

     

    One pass of erase with Zeroes or a random pattern will erase all the files on the drive, including all data blocks. No data can be obtained from the drive unless you have a clean room and can dis-assemble the drive and use expensive specialized equipment to analyze the portions of magnetic patterns that may still be present in some areas. This is sufficient for all but nuclear secrets.

     

    For SSD drives:

    After any erase, data blocks are not accessible to common Utilities.

     

    If you disassemble the drive, it is possible that custom electronics could cause the drive to give up a few data blocks. The military suggests the only solution for this is shredding the chips on the drive.

  • by BobTheFisherman,

    BobTheFisherman BobTheFisherman Jun 19, 2016 8:35 AM in response to pjttty
    Level 6 (15,443 points)
    Jun 19, 2016 8:35 AM in response to pjttty

    What to do before selling or giving away your Mac - Apple Support

  • by leroydouglas,

    leroydouglas leroydouglas Jun 19, 2016 8:54 AM in response to pjttty
    Level 7 (23,789 points)
    Notebooks
    Jun 19, 2016 8:54 AM in response to pjttty

    pjttty wrote:

     

     

    Also, I'm aware that 7-pass is overkill but I'd rather do it for peace of mind.

     

     

    18 hours of erase time  on a 500 GB drive—I would have to agree is overkill.  I would rethink this necessity.