Selling Mac Mini - Is Erasing Free Space Necessary?

Discussion in 'Mac mini' started by mstgkillr, Oct 30, 2014.

  1. mstgkillr macrumors regular

    Joined:
    Feb 11, 2012
    #1
    I'm preparing my Mac Mini with 1TB Fusion for sale. Is it necessary or advisable to erase the free space by zeroing it out? If so, is one pass sufficient?
     
  2. talmy macrumors 601

    talmy

    Joined:
    Oct 26, 2009
    Location:
    Oregon
    #2
    If you don't care what the purchaser might see, then don't bother.

    If you have sensitive information (SSNs, financial statements...) a one pass erase will keep it out of the hands of all but dedicated snoops.

    Information about your embezzlements or drug deals? Go for the 7 pass, at least. :)
     
  3. Butchie-T macrumors regular

    Joined:
    Oct 29, 2014
    Location:
    Colorado
    #3
    Time is a small price to pay for....

    ...peace of mind. Run the 7 pass on it before you sell it. That way you know that there is a high degree of never seeing any data bits in that free space again.
     
  4. talmy macrumors 601

    talmy

    Joined:
    Oct 26, 2009
    Location:
    Oregon
    #4
    Just had another thought. If you are concerned about somebody seeing your drive content then you should have been using FileVault 2 to encrypt the contents. With FileVault 2 you can just reformat the drive unencrypted and not worry about erasing.

    Why even mention this? Well if someone wants your data for nefarious reasons they are more likely to steal your computer than wait for you to sell it and then buy it from you!
     
  5. Altis macrumors 68030

    Joined:
    Sep 10, 2013
    #5
    I don't think OP is concerned so much about people actively trying to steal their data specifically, but the idea of sending off a hard drive with personal data traces on it and no idea where it could end up.
     
  6. talmy macrumors 601

    talmy

    Joined:
    Oct 26, 2009
    Location:
    Oregon
    #6
    You are right, he isn't. But I'm saying he probably should be if he is concerned enough about privacy that he is worried about the purchaser of his system looking at his free space.
     
  7. rigormortis macrumors 68000

    rigormortis

    Joined:
    Jun 11, 2009
    #7
    look back to all those android phones that avast bought and how easy it was to recover private information

    I'm trying to sell my beater - mini on eBay. i did the 7 pass. i call it a beater mini because the optical drive isnt completely guaranteed and its tabs on the bottom plate are broken


    you can do a 7 pass and stop after about 3 passes, thats good enough.

    i wonder about the encryption. i wonder if doing a quick erase on a file vault 2 drive erases the block cipher similar to what happens on an iPhone 3gs and above

    the one thing mac users like is if you do a 7 pass erase and then install os x for them. but before it reboots, shut it down. that way, when the new owner buys your used mac, he is greeted by the welcome to os x movie. just like he would if he bought a new computer.
     
  8. philipma1957 macrumors 603

    philipma1957

    Joined:
    Apr 13, 2010
    Location:
    Howell, New Jersey
    #8

    yeah back on snow leopard .

    I sold so many of them I had 2 or 3 'fresh' copies and would install them to get the movie to play. That little white box mini was nice.
     
  9. talmy macrumors 601

    talmy

    Joined:
    Oct 26, 2009
    Location:
    Oregon
    #9
    Quick erase would be just fine with a FileVault 2 drive. Yet another reason to use FileVault 2.
     
  10. scenemissing macrumors member

    Joined:
    Jun 18, 2010
    #10
    A quick erase will be fine in 99.9% of the cases. The extra .1% would be if the buyer ran a data recovery tool on the drive to look for files.

    If that prospect scares you, do the 1 pass zero wipe. Don't bother with the 7 pass - that standard is massively out of date. It comes from the era of 80 meg hard drives with comparatively wide track widths. Modern drives are completely unrecoverable after 1 pass of zeroes, even using DriveSavers level tech.

    If you're doing anything that requires more security than 1 pass (you work for the NSA, you're a drug lord, you're super paranoid) that you should physically destroy the disk.
     
  11. rigormortis macrumors 68000

    rigormortis

    Joined:
    Jun 11, 2009
    #11
    actually the older standard for "wider track drives" was 3 passes. it was only recent that it was revised to 7 passes.

    the recent problem with android devices, where avast purchased 24 android phones on eBay and were able to retrieve thousands of pictures should scare people into doing a 7 pass erase.

    a quick format only erases the file allocation tables and boot sectors., all your data is still intact.

    when selling computers on eBay you have to realize that you are selling your computer with your personal information potentially still on it to complete strangers and you have no idea where that computer will finally end up.

    the iPhones have a special area of effaceable storage that clears its block cipher, so the file system cannot be retrieved. but i recently sold my iPhone 5, so now i have to worry if i shipped it to an empty house and the guy is trying to scam me, but at least i know my data is safe
     
  12. scenemissing macrumors member

    Joined:
    Jun 18, 2010
    #12
    That's just what I was saying though, "quick erase" is not actually eraseing anything. There is no reason to do a 7 pass wipe vs a 1 pass wipe except for politics. There are reasons to do a 1 pass vs a quick erase.
     
  13. cfedu macrumors 65816

    cfedu

    Joined:
    Mar 8, 2009
    Location:
    Toronto
    #13
    This
     
  14. rigormortis, Nov 9, 2014
    Last edited: Nov 9, 2014

    rigormortis macrumors 68000

    rigormortis

    Joined:
    Jun 11, 2009
    #14
    use file vault. and your whole 0 pass erase vs 7 pass erase argument is moot. and your quick erase will still be protected.

    i would definitely use 3 passes. you don't know where that computer could wind up going. it could be sold overseas. just do the 7 pass anyway and maybe stop after 3. the extra time it takes to sit there and wait for the hard disk to wipe 7 times is not with all the bickering. so it takes an extra day. who the heck cares, you gain extra security.

    when i suspect one of my drives might have problems, i used to run sprinrite, now i use hdd regenerator, and that excersises the disk more then a 7 pass could ever do.

    running more then 1 pass could theoretically reveal a bad sector or a failing drive... so there.. i just made made 7 pass worth it. you can stop posting now. this thread is done , haha

    i posted the heck on another thread about s.m.a.r.t. sensors. to summarize. all hard drives have bad sectors. nobody can manufacture a hard disk drive without any errors at all. and they have intelligence that automatically maps bad sectors to its bank of spares and also automatically retry if it reads or writes the data wrong. when the hard drive fails, it blows its s.m.a.r.t. sensor and that notifies the computer's bios or operating system. once the computer reports a s.m.a.r.t. sensor has been tipped you have to throw the drive away and replace it. no utility can clean or repair or do anything to bring that hard disk back to the way it was before.
    please. save your money. don't spend money on software to "diagnose" your smart error. get the serial number, contact the drive manufacturer or apple care, and see if its under warranty.


    so therefore. by doing a 7 pass erase, you are not just taking the extra step of protecting your identity, which is more important now then ever, but you are also giving that drive a workout to make sure it is still good, and that it has not "grown" any new bad sectors.

    ever since IDE came out in 1985 the ability for the home user to low level format the hard disk has been made impossible by the hard disk manufacturer. they are pre-low level formatted or " servo written " at the factory. the only diagnostics or restoration we are allowed to do now is wiping the hard drive more then once to make sure the drive is still good. that alone i believe makes more then 1 pass worth it

    that argument of "wider track drives " is total nonsense.
     
  15. rigormortis macrumors 68000

    rigormortis

    Joined:
    Jun 11, 2009
    #15
    all hard drives manufactured since 1985 have stronger magnetic fields. due to their more powerful magnets. this is why the the standard was increased to 7. the high power magnet is incapable of changing any sector markings. any requests to do any low level format operation is blocked by the hard disk's firmware.

    that is why we have 7 passes.


    thank you for playing
    please come again
     
  16. rigormortis macrumors 68000

    rigormortis

    Joined:
    Jun 11, 2009
    #16
    oh great. its a fusion drive. there is no reliable way of completely erasing the SSD module. even with 35 passes.turn on file vault. erase hard disk . then your okay
     

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