Disk Utility secure erase "7 pass secure erase"

Discussion in 'OS X Mavericks (10.9)' started by Appletise, May 4, 2014.

  1. Appletise macrumors member

    Joined:
    Sep 19, 2012
    #1
    why does it take so long for the most secure erase. it is estimated 2 days 15hrs for my 500GB HDD. does cancelling it after several hours still make it more erased than the fastest erase?
     
  2. m4v3r1ck macrumors 68020

    m4v3r1ck

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    The Netherlands
    #2
    Are you selling it?
     
  3. yjchua95 macrumors 604

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    Apr 23, 2011
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    GVA, KUL, MEL (current), ZQN
    #3
    For a HDD, that estimated time is perfectly normal.

    It has to write 3500GB of data to your HDD to empty it.

    The best realistic rate is that it'd take one day to write 3500GB of data to it in a 7-pass erase, assuming that it operates at an average of 100MB/s.

    500x7=3500GB
    3500GB=3584000MB
    Time taken: 35840 seconds / 597 minutes / 24.8 hours.

    If you have a 500GB SATA3 SSD instead, assuming that it operates at 500MB/s
    Time taken: 7168 seconds / 119.5 minutes / 2 hours.
     
  4. BrianBaughn macrumors 601

    BrianBaughn

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    Baltimore, Maryland
    #4
    Good question. One would assume it completes a pass then starts the next one but I don't know and haven't seen the process explained in enough detail. If it does, then the answer should be "yes". But if it does 7 passes a sector (or some other division) at a time then the answer would be "no".
     
  5. FreakinEurekan macrumors 68040

    FreakinEurekan

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    Sep 8, 2011
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    Eureka Springs, Arkansas
    #5
    The answer is "Yes" either way - but for different values of "more erased". Under scenario 1, the entire disk is "more erased". Under scenario 2, the entire disk is "as erased" and the portion completed up to cancellation is "more erased".
     
  6. Appletise thread starter macrumors member

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    Sep 19, 2012
    #6
    its been running for over a day, but it goes into shut down or log off? and l have to select "don't quit" in disk utility window because its just been sitting there with no key pressed, so should l go to system preferences, energy saver and select "never" "computer sleep" ?
    if l quit the erase now, would it still be more erased than a quick erase, which takes seconds?
     
  7. BrianBaughn macrumors 601

    BrianBaughn

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    Feb 13, 2011
    Location:
    Baltimore, Maryland
    #7
    I was thinking of a chalkboard analogy for scenario 2...like if you go over 1/10 of the chalkboard 7 times, then move to the next 1/10 and so on. If you stop the process halfway, you can still see half the chalkboard.
     
  8. Appletise thread starter macrumors member

    Joined:
    Sep 19, 2012
    #8
    thanks for info, l will wait the extra day, it is now at pass 4 of 7 but as my last post states, the process stops since the computer is not used and after a certain time it has 1 of 2 windows that says: "Operations still in progress Disk utility still has some operaitons in progress." and 2 buttons in that window "Quit" "Don't Quit"
    the other window says:
    "you haven't been logged out because the applicaiton disk utility failed to quit. to try logging out again, quit disk utility and click try again."

    how do l prevent this? so can get this done asap!

    thanks
     
  9. Alrescha macrumors 68020

    Joined:
    Jan 1, 2008
    #9
    Next time use one pass. Anyone who can recover data after a one-pass secure erase already has a backup of your stuff :)

    A.
     
  10. FreakinEurekan macrumors 68040

    FreakinEurekan

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    Sep 8, 2011
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    #10
    True if you're comparing 1-pass to 7-pass. But basic erase is really 0-pass, just erasing the "directory" - which also is done in an aborted 7-pass.

    I don't know which scenario is accurate; I would guess 7 sequential start-to-finish passes.
     
  11. Appletise thread starter macrumors member

    Joined:
    Sep 19, 2012
    #11
    Unfortunately it didnt complete, last time l saw it was at step 5 of 7. When l woke up it said "secure erase disk failed
    securely erasing data to prevent recovery failed" with an "OK" button

    and there was no charge on the battery, l didnt plug it in as l didnt want to overcharge the battery.

    so is the HDD now more secure than a quick 1 step erase?
     
  12. mikecwest macrumors 6502a

    mikecwest

    Joined:
    Jul 7, 2013
    #12
    Unless your Mac is really ancient, or defective in some way, you can safely leave your mac plugged in for the time it takes to erase the drive.

    You should not have to worry about overcharging your laptop, however most would agree that its not good to leave it plugged in permanently.
     
  13. emt1 macrumors 65816

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    Jan 30, 2008
    Location:
    Wisconsin
    #13
    7 pass erase is excessive. nobody has recovered data from even a one-pass wipe.
     

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