Erase an SD card completely

Discussion in 'OS X Mavericks (10.9)' started by macstatic, Jan 4, 2017.

  1. macstatic macrumors 6502a

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    Oct 21, 2005
    #1
    Is there a way to erase an SD memory card (connected to my Mac via a card-reader) completely without damaging the card? I don't want the new owner of the card to be able to recover old files on it.

    And yes -I am aware of the "secure erase" option in Disk Utility, but understand that with multiple passes on a memory card (or SDD) you're basically shortening its lifespan considerably.
     
  2. Bruno09, Jan 5, 2017
    Last edited: Jan 5, 2017

    Bruno09 macrumors 68020

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    #2
  3. macstatic thread starter macrumors 6502a

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    Oct 21, 2005
    #3
    Good idea!
    I didn't quite understand the part about choosing the startup disk though (marked in bold below):

    .. so should I enable the (now encrypted) SD card as the startup disk? Obviously this won't work as it's a previously erased card for a digital camera.
     
  4. KALLT macrumors 601

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    Sep 23, 2008
    #4
    No, what Bruno meant is that you should convert or reformat the SD card as ‘Mac OS Extended (Journaled, Encrypted)’. However, doing so will waste write cycles as well. Doing a ‘zeroing’ secure erase is usually enough.
     
  5. macstatic thread starter macrumors 6502a

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    Oct 21, 2005
    #5
    Where do I find the zeroing secure erase option? In my Disk Utility (version 13/OSX 10.9.5), when I click on "Security options" I only get a slider where it ranges from "Fastest" to "Most secure". No mention of "Zeroing" anywhere as far as I can see.
     
  6. KALLT macrumors 601

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    Sep 23, 2008
    #6
    The scale should have a label underneath it. It should say something along the lines of ‘writing zeros to the disk’.
     
  7. macstatic, Jan 8, 2017
    Last edited: Jan 8, 2017

    macstatic thread starter macrumors 6502a

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    #7
    Ah, got it! Here's a screenshot.
    So basically this just fills up the memory card with zeroes until it's full? So the process won't reduce its life other than what filling it up with photos/videos or whatever would?
    diskutil_zeroes.png
     
  8. Weaselboy Moderator

    Weaselboy

    Staff Member

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    Jan 23, 2005
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    California
    #8
    I think you are thinking of older OS X versions. The newer versions are like this.

    Screen Shot 2017-01-08 at 1.29.56 PM.png
    --- Post Merged, Jan 8, 2017 ---
    Yes the effect is one write cycle like if you have filled the drive with files then deleted them.
     
  9. macstatic thread starter macrumors 6502a

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    Oct 21, 2005
    #9
    Oops!, sorry -I forgot to upload the screenshot (update: it's uploaded into the previous message now). Yes, I'm on 10.9.5.

    So after writing a single cycle with zeroes like that it would have to take some (expensive) specialized service to recover anything on it and not just a regular OSX "undelete" tool like Disk drill, Data rescue, Photo rescue (and I few others which slipped my mind) to get them back?
     
  10. KALLT macrumors 601

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    Sep 23, 2008
    #10
    That is only possible if there is some over-provisioned part where some data might have survived the operation, but that would be a very small part, if it is at all present. Overwritten memory blocks are gone.
     

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