Questions On 7 Pass Secure Erase

Discussion in 'MacBook Pro' started by AppleUser2, Jul 17, 2009.

  1. AppleUser2 macrumors member

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    Jun 10, 2009
    #1
    Can I just check:

    With about 30G to erase should it be taking over 8 hours to complete the process?

    If I pick "skip" for the 6th pass will this ruin the whole process or just skip to the 7th pass which I assume will still mean that my erase process has been pretty thorough (6 passes)?

    I have the main disc selected - titled Hitachi but there is a drive underneath it, indented to the right, as well called Macintosh HD - do I need to do all this again for this drive or is the Hitachi drive the "master" and I am erasing the "Macintosh HD" at the same time as doing the "Hitachi" drive?

    Thanks
     
  2. matthewscott661 macrumors 6502

    matthewscott661

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    Chicago
    #2
    Yes. If you select the physical drive then it will delete all partitions on that drive.

    And it takes a long time no matter how much data was on the drive. This is because when you delete things they don't actually get erased, they are just unable to be accessed. The data is still there, and when you erase using 7-pass, the entire drive has to be rewritten to get rid of the data.
     
  3. AppleUser2 thread starter macrumors member

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    #3
    Matthew

    That's great news, thanks. I really don't have the time to do this all again on the partition drive so it is good to read that I don't. It has been running for about 7 hours so far, is on pass 5 and has been stuck at pass 5 with 3 hours estimated completion time for the last three quarters of an hour. Hopefully in a few minutes it will jump to only an hour or so to go on this pass.

    Thanks for the help.
     
  4. DoFoT9 macrumors P6

    DoFoT9

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    #4
    zeroing data means that it reads EVERY byte on the hard drive and individually changes it to a "0", even if it is already a "0" it will do it again, making it rather secure. it has to do this 7 times! so its quite an effort.

    if your HD is 320gb (for example, im not sure what size yours is), and it can read/write at a sustained rate of say 40mBps, that is roughly two hours per pass, so 8 hours doesnt sound too bad at all.

    oh and to answer your other uestion about the drive being "indented", you should erase the very first one on the list (e.g. the highest point in the hierarchy).
     
  5. AppleUser2 thread starter macrumors member

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    #5
    Thanks - the drive is 250G. Sounds like zeroing data is pretty secure, perhaps should have gone for that. Well into the 7 pass process (pass 5) so will stick with this for the time being.
     
  6. DoFoT9 macrumors P6

    DoFoT9

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    #6
    yes im afraid you will have to, the risks are too high to try and stop it. let us know how it goes!

    zero pass would be more then enough in normal situations :)
     
  7. walshlink macrumors regular

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    Oct 21, 2007
    #7
    Unless you are DoD, 1-2 passes is quite enough.
     
  8. alphaod macrumors Core

    alphaod

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  9. AppleUser2 thread starter macrumors member

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    Jun 10, 2009
    #9
    Thanks guys - yes does look like I went a bit over the top. Will know for next time! Only an hour an 5 minutes to go!
     
  10. RED™ macrumors regular

    RED™

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    #10
    I am erasing my 500 GB external drive with the 7 pass secure erase just in this moment and it's far away from 8 hours... 1 day 11 hours to go ;)

    Of course it is more than 320 GB, but even 8 hours sound a bit tiny for these.
     
  11. AppleUser2 thread starter macrumors member

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    Jun 10, 2009
    #11
    Now you have me worried that it did not work correctly for me. Ah well too late now, machine passed on.
    I do wonder if over a day to complete is too long though?
     
  12. NovemberWhiskey macrumors 68030

    NovemberWhiskey

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    May 18, 2009
    #12
    I just did a 7-pass erase for my mbp.

    I have a 400 gb partition for OSX and a 100 Gb partition for Bootcamp. I did the erases individually, and the OSX took ~15 hours and IIRC the Bootcamp partition took 5 hrs or so.

    I would recommend just doing the whole thing together because if you do it individually, it does not get rid of your partition.

    I think if you have the time, just set it some time in the evening and go to sleep. When you wake up, you should only have a couple of hours left.

    Anyone try the 35-pass erase? That should be fun...
     
  13. RED™ macrumors regular

    RED™

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    #13
    Oh great, I can't believe it: While it was at the 2nd erase phase my MBP had more than 3 hours of battery left and so I let myself watch some TV and like usual I fell asleep :rolleyes:

    And of course I did not control my battery and so it shut down! :eek: Do I have to do the procedure from the beginning or would it be enough to just make the 1 pass secure erase after having now a 1.5 pass secure erased drive?

    It drives me nuts and I know it was stupid not taking care of it... I'm ashamed so please save it :eek:
     
  14. DoFoT9 macrumors P6

    DoFoT9

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    #14
    why oh why did you do this pass if you dont know what it means??? the time taken differs from each brand/model of HD, because it is a laptop HD the read/write speeds of the drive are slower, so the time taken to finish are of course going to be longer.

    oh god.. the drive should be ok. when you awoke the computer did it continue erasing?? just do it again.. but this time just do the 1-pass... 7-pass is a bit excessive.
     
  15. aaron11193 macrumors regular

    aaron11193

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    #15
    what are you all erasing your drives for anyway?
     
  16. RED™ macrumors regular

    RED™

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    #16
    Thank you DoFot9 - no it did not continue it said in german "data erasing progress failed".

    I chose the 7 pass method because I'm selling my external hard drive and I read in various forums that the 1 pass wouldn't be secure enough.

    Anyway, I hope that 2.5 pass is secure enough now, I don't have the nerves to stand the constant noise of that drive anymore :eek:
     
  17. alphaod macrumors Core

    alphaod

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    #17
    I think Disk Utility's implementation is just slow. If I use DBAN it takes about 5 hours only for a DoD-Short (3 pass I think).
     
  18. DoFoT9 macrumors P6

    DoFoT9

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    #18
    ok i figured that it would cancel itself, was just asking. 2.5 pass will be fine. maybe you could have done a single-pass twice?? anyway do what you like, goodluck :)

    maybe Disk utility uses a different type of erasing method? maybe it uses different "phases" of data to over-write, or double checks.. who knows though .
     
  19. SnowLeopard2008 macrumors 604

    SnowLeopard2008

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    #19
    I read somewhere about a study that showed many data recovery companies can't recover drives that haven't been erased with the 1 pass option. So you're pretty much safe. Doing so many passes wastes time and even if you let the drive be, no one will recover stuff from it.
     
  20. RED™ macrumors regular

    RED™

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    #20
    Thanks everyone, I feel pretty safe now. The HDD is packed and ready for shipment.

    I want to apologize to the OP for hijacking his thread, but maybe he learned something just as I did :)
     
  21. AppleUser2 thread starter macrumors member

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    Jun 10, 2009
    #21
    No problem - it's all interesting stuff. I think the main thing I have learnt is that next time if I am really pushed for time a 1 stage pass should be pretty safe.
     

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