Fun fact, files don't just get instantly nuked when you delete them, those areas are just marked with a deleted flag and only when you start adding new files it gets overwritten.

That why some people send a bunch of 0s to their partition to completely wipe it.

https://unix.stackexchange.com/questions/636677/filling-my-hard-drive-with-zeros

[–] Fluke@feddit.uk 14 points 1 week ago* (last edited 1 week ago) (3 children)

Then 1s, then a pattern of 1s and 0s, then the inverse of that pattern, then another pattern, for a number of cycles.

Data can actually be recovered beyond multiple overwrites, if enough time and money is thrown at it.

[–] wabasso@lemmy.ca 17 points 1 week ago

If there is something on your disk that a state actor is going to use magnetic microscopy to try to recover, it seems absurd to worry about still being able to use that hard drive and not just crush/melt it to be sure.

[–] Buddahriffic@lemmy.world 9 points 1 week ago (1 children)

Is that still the case with SSDs? I understood it to be a property of magnetic disks, and only possible because the drives can be disassembled and then read with a more sensitive reading head. I can't think of a way to do that with flash circuitry unless it's already designed to do that.

[–] RobertoOberto@sh.itjust.works 5 points 1 week ago (1 children)

Relevant: https://www.stellarinfo.com/blog/myths-about-disk-wiping-and-solid-state-drives/

[–] Buddahriffic@lemmy.world 7 points 1 week ago

Oh yeah, the bit where SSDs move sectors around for wear evening is important. Because of that, it's possible to completely fill up an SSD after deleting files and still have those files recoverable from the flash chips themselves. Without that secure erase, as I understand it, if a sector gets marked "bad", whatever data is there might stay there forever (or at least as long as the cells hold a charge).

So there's no benefit to writing multiple passes over deleted data on SSDs as far as the flash is concerned, but multiple passes might make it more likely for the controler to actually direct those extra writes to a sector actually storing the data (though the odds might be low unless you're overwriting all free space, though even that depends on how much space is free vs how many "spare" sectors there are, and even then it might be impossible to get it to write to a sector marked "bad").

[–] JackbyDev@programming.dev 3 points 1 week ago

They keep saying that but those Bitcoins are still in the dump. (I'm aware it's not comparable since having the drive in hand versus missing is a huge difference. Just a little joke.)

load more comments (10 replies)