Viewing a single comment thread. View all comments

bob0979 t1_iy4blr4 wrote

Reply to comment by yoshhash in eli5 How is computer memory deleted? by unlikemike123

Many drive cleaner tools will have a tool to wipe free space. They write over every bit that is not occupied with 'undeleted' data or stuff you're using. They replace everything not in use with new junk data that could just be 00000001 for every bit. This takes a fair bit of time but doing this a couple of times can remove any trace of what a specific bit says or even used to say.

If you save somethinn as 'file.name' and it's contents are 00000111 then delete it, it stays as 00000111, but if you delete it then wipe free space it changes that 00000111 to something useless.

5

Grezzo82 t1_iy5aoeu wrote

“A couple” is sometimes not enough, but a few more is considered secure enough for most contexts, though gov will often physically shred the disks to be sure.

I only know for sure with macOS, but I image isn’t this applies to all: the OS has a built in secure erase feature that will overwrite a whole disk enough times to be confident that the data is irrecoverable

1