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posted by mrpg on Friday March 17 2017, @05:14AM   Printer-friendly
from the encrypt-for-the-win dept.

How do you destroy an SSD?

First, let's focus on some "dont's." These are tried and true methods used to make sure that your data is unrecoverable from spinning hard disk drives. But these don't carry over to the SSD world.

Degaussing – applying a very strong magnet – has been an accepted method for erasing data off of magnetic media like spinning hard drives for decades. But it doesn't work on SSDs. SSDs don't store data magnetically, so applying a strong magnetic field won't do anything.

Spinning hard drives are also susceptible to physical damage, so some folks take a hammer and nail or even a drill to the hard drive and pound holes through the top. That's an almost surefire way to make sure your data won't be read by anyone else. But inside an SSD chassis that looks like a 2.5-inch hard disk drive is actually just a series of memory chips. Drilling holes into the case may not do much, or may only damage a few of the chips. So that's off the table too.

Erasing free space or reformatting a drive by rewriting it zeroes is an effective way to clear data off on a hard drive, but not so much on an SSD. In fact, in a recent update to its Mac Disk Utility, Apple removed the secure erase feature altogether because they say it isn't necessary. So what's the best way to make sure your data is unrecoverable?


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  • (Score: 0) by Anonymous Coward on Friday March 17 2017, @01:02PM (1 child)

    by Anonymous Coward on Friday March 17 2017, @01:02PM (#480371)

    And that would be the same for a HDD. There are spare sectors (up to the full capacity) in HDDs, too, and the sector mapping is abstracted in a comparable way to SSDs. The difference being that physical proximity matters more in HDDs than in SSDs.

    Spinning drives have extra sectors, yes, but unlike SSDs the extra storage is not routinely used. They are only used when the original sectors fail. You can check the SMART counters to see if this has happened on your drive(s).

    Typically, having more than zero remapped sectors on a hard disk is an indication of imminent failure.

  • (Score: 2) by Immerman on Friday March 17 2017, @03:52PM

    by Immerman (3985) on Friday March 17 2017, @03:52PM (#480465)

    >Typically, having more than zero remapped sectors on a hard disk is an indication of imminent failure.

    Is it? That's not my experience. My understanding was that the are a number of highly localized manufacturing flaws that can be present on a platter that may cause small clusters of sectors to fail, without indicating anything substantial about the drive as a whole. It's when you start seeing the number of bad sectors climb rapidly that drive failure is imminent.

    Of course, best practice is to replace the drive at the first sign of trouble just in case it's a sign of something serious, since a serious problem can worsen very rapidly and your first warning may also be your last. But I believe that if you have a drive with only a few bad sectors, the odds are high that it doesn't have any serious problems - hammer it hard, with say several full-disk rewrites, and if the number of bad sectors stabilizes quickly you've probably got a lot of life left in the drive.

    I might not trust it with anything really critical, but I wouldn't really trust *any* single drive for that. I've had many, many drives work without problems for years with a few bad sectors, until they were eventually retired as obsolete. And only a few that have actually developed serious problems, both of which failed so fast that I salvaged data file by file starting with the most critical because the computer would inevitably crash at some point and usually take the remainder of the active folder with it.