On Wed, Sep 14, 2011 at 09:02:42AM -0400, shawn wilson wrote: > On Sep 14, 2011 8:51 AM, "Robert Parker" <rlp1938@gmail.com> wrote: > > What's wrong with dd if=/dev/zero of=/dev/sdX for SSDs? > > Well, I remember hearing that data is recoverable to some degree unless the > media is destroyed. Is there no trace of a bit being stored after it is 0'd > out on an ssd? With regards to spinning platters, it's FUD. Today's drive densities are so great, that there is no room for the actuator to "jitter" the data off the track, as was problematic with drives in the early '90s and earlier. If the actuator doesn't put the data _exactly_ where it was last time, you could suffer data loss. So, writing a single pass of zeros will overwrite every bit, and there will be no "left-over" data that can be determined as to what was overwritten. With SSDs, it's a different story. We've had HDD secure erasing solved for ages, but SSDs appear to be problematic. The same methods you would use for securely erasing an HDD should not be the same you use on an SSD (or any solid state media, such as USB thumb disks for that matter). Ars Technica ran two "Ask Ars" articles that pretty much explain the problem we are facing with SSDs: http://arstechnica.com/ask-ars/2011/01/askars-solid-state-drives-and-garbage-collection.ars http://arstechnica.com/ask-ars/2011/03/ask-ars-how-can-i-safely-erase-the-data-from-my-ssd-drive.ars > The other thing is ease of use. I'm not going to tell my grandmother 'type > dd of......' no, not happening. But, 'go get the drill and you should notice > a circle outlay; you want to drill through the disc a third off center of > that circle' - that, she can manage just fine. If your grandmother is running a GNU/Linux desktop, then she should have no problem pulling up a terminal and typing "dd if=/dev/...". Then again, just physically bending the platters is enough to prevent every data recovery organization out there to get to your data, unencrypted or not. -- . o . o . o . . o o . . . o . . . o . o o o . o . o o . . o o o o . o . . o o o o . o o o
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