How long does it take to 7pass erase a SSD

Discussion in 'MacBook Air' started by xkmxkmxlmx, Jul 20, 2011.

  1. xkmxkmxlmx macrumors 6502a

    xkmxkmxlmx

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    Apr 28, 2011
    #1
    I know doing a 7pass erase, depending on HDD size, can take quite a while.

    Does anyone know how long it generally tales per erase on a 128GB SSD?

    Thanks!
     
  2. ECUpirate44 macrumors 603

    ECUpirate44

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    #2
    I'd say between 7-8 hours. Unless your covering up nuclear missile launch codes, a 0 pass will be fine.
     
  3. WardC macrumors 68030

    WardC

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    #3
    by 0 pass he means a single pass with zeros, One-time pass erase (zero drive) which will write zeros over the entire contents of your drive. It will basically make any information previously stored on your disk 99.999% unrecoverable with any Disk Recovery software on the market.
     
  4. xkmxkmxlmx thread starter macrumors 6502a

    xkmxkmxlmx

    Joined:
    Apr 28, 2011
    #4
    Yes, I know 1 pass is generally safe. Still gonna do a 7 pass. You never know.

    8 hours seems kind of high, though, no?

    I mean, a 1tb HDD single pass takes about 4 hours or so.

    There is no speed advantage to it being a SSD over a HDD?

    It doesn't matter at this point, I guess, but now I am just curious. Guess I'll know soon :)
     
  5. rcp27 macrumors regular

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    #5
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    The point of a 7 pass erase is because on a spinning platter magnetic disk the write process changes the state of the disk enough to be read at the new state but leaves potentially recoverable traces of the old state. Hence a multi pass wipe repeats the process several times to reduce these traces to an effectively unreadable state. The different switching characteristics of an SSD suggest to me that this kind of process isn't really necessary.
     
  6. PaulWog Suspended

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    Jun 28, 2011
    #6
    Passing your hard drive will reduce its lifespan significantly.

    I'd just do a 2-pass.
     
  7. Shaun.P macrumors 68000

    Shaun.P

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    #7
    I performed a 7 pass erase on an 96GB SSD drive going back to Amazon - the Kingston V+100 which is pretty much on par (speed wise) with Apple's SSD drives.

    The procedure took 50 minutes. On a traditional hard drive this will be 7-8 hours.
     
  8. xkmxkmxlmx thread starter macrumors 6502a

    xkmxkmxlmx

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    Apr 28, 2011
    #9
    Thank you for answering the actual question :)

    And thanks for this info. I will read it all this evening.
     
  9. KPOM macrumors G5

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    Oct 23, 2010
    #10
    Bugout is right. Doing a true erase on an SSD is very difficult, and what Apple gave us with Snow Leopard doesn't cut it. The best option may be to boot with a Linux device from USB, and then try to run a secure erase command from that, and then restore Snow Leopard using your USB key.

    I plan to use full disk encryption when I get the Rev E (the Core i5/i7 is MUCH better suited to this than the Core 2 Duo), but I'm not sure what this means for the need to do a secure erase upon disposal.
     
  10. Tech198 macrumors G4

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    Mar 21, 2011
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    Australia, Perth
    #11
    I'm just wondering if anyone knows, why Apple can get around their own wear leveling on flash built into w iOS "so you can do as many erases as possible/delete and it won't wear out", but SSD manufactures, including Apple's own SSD's included with Macbook Air's/Retina cannot get round wear leveling , and must rely on *less efficient* methods like TRIM.
     
  11. Weaselboy Moderator

    Weaselboy

    Staff Member

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    Jan 23, 2005
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    California
    #12
    Suggestion for OP to get around this issue. Turn on Filevault for the SSD and wait for encryption to complete. This turns the entire disk into an encrypted core storage volume. Then use Disk Util to erase the entire disk. So even if someone managed to restore some of the date you erased it would still be encrypted.
     
  12. Newtons Apple Suspended

    Newtons Apple

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    #13
    It only take about 15 seconds to erase an SSD.

    Microwave oven.:p
     
  13. scaredpoet macrumors 604

    scaredpoet

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    Apr 6, 2007
    #14
    This. On an SSD, FileVault is the only way to be sure.

    A 7-pass erase on an SSD might severely reduce its lifespan, or might prove ineffective. Or both.
     
  14. JGruber macrumors 6502

    Joined:
    Feb 13, 2006
    #15
    Are there any performance hits to using Filevault? Example, on my 203 MBA, 512GB drive, if I turn it on, will I lose a ton of speed?

    I thought I remember hearing in the past, if you run encryption on an SSD drive, you take a big performance hit.
     
  15. Weaselboy Moderator

    Weaselboy

    Staff Member

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    California
    #16
    There is a very small hit in disk read/write speeds, but it is not noticeable, particularly on newer Macs with an SSD like yours. Here are some tests.
     

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