Secure Erase SSD vs wear and tear

Discussion in 'Mac Basics and Help' started by stubeeef, Aug 16, 2016.

  1. stubeeef macrumors 68030


    Aug 10, 2004
    I'm curious if my habit of using secure erase is going to limit the life of my SSD in a stock mid 2013 MacBook Air.

    To be clear I'm talking about secure erase of files not the entire drive.

    Any info is helpful!

  2. Weaselboy Moderator


    Staff Member

    Jan 23, 2005
    It will reduce the life some in theory, because you are introducing one extra write cycle to the NAND cells with that data. But that said, as a practical matter, I think the odds are you will have trashed that MacBook well before the drive ever wears out.

    Those things can handle a LOT of write cycles. Give this test a look.

    I think it might be a noticeable difference if you say worked with 10GB video files all day and trashed then secure erased those over and over all day... that could add up to some reduced lifespan perhaps. But any kind of more average usage, I just don't think it will be noticeable.
  3. stubeeef thread starter macrumors 68030


    Aug 10, 2004
    Thank you Weaselboy! I was in the habit of doing secure erases from the old hard drive days to keep my drive clean. I guess I don't need to do that since I have no sensitive trash!
  4. gnasher729 macrumors P6


    Nov 25, 2005
    "Secure erase" means overwriting the contents of files multiple times with random data, to make sure that nobody can read it. (The theory is that if you overwrite you sensitive data with zeroes on a magnetic hard drive then some remaining magnetism could be read with sophisticated hardware and your data could be reconstructed). As far as I know that theory hasn't been true anymore for a few years - the amount of magnetism on a modern hard drive is supposedly so tiny that after overwriting with zeroes once, nothing is readable. For SSD drives, this was never true: Overwritten is overwritten is gone forever. Except there might be copies in different places, which overwriting multiple times doesn't erase.

    It's pointless with an SSD drive, and reduces the time until the drive wears out.
  5. KALLT macrumors 601

    Sep 23, 2008
    To elaborate: The incompatibility with SSDs and ‘secure erase’ arises, because (1) there is no such thing as overwriting on an SSD, because in order to write data to a particular storage cell, the cell has to be zapped first (at which point the data is gone); and (2) the system does not get to decide to which cells data is written, but only tells the SSD’s controller that it should write data. The controller cannot distinguish between what the OS considers overwriting and normal writing. Once it knows that the OS wants to change written data, it will write the changes to new cells and mark the cells that contain the old data as stale, ready for garbage collection or trimming. The only benefit that a secure erase has, is that the SSD will eventually zap stale cells. When that happens depends on a variety of factors, such as the size of the SSD, the available space, the garbage-collection routine and others. Secure erasing is thus not secure and it is marginally, if at all, a performance measure to help the garbage collection along, at the cost of write operations. Unless you know the ins and outs of your particular SSD and its behaviour, doing these kinds of ‘optimisations’ is not recommended.
  6. stubeeef thread starter macrumors 68030


    Aug 10, 2004
    Great stuff-thnks y'all I've unchecked erase securely. Like I said I thought there was a benefit on a hard drive-but with SSD I just don't see it.

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