Why does deleted data stay on a HDD once written, waiting to be overwritten, as opposed to being removed when requesting deletion?
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It takes a lot more time to go and remove the data, especially on older spinning discs
Got a 10 GB ripped bluray movie you don’t want any more? The way that we have deleting setup today it goes and clears the entries in the file time and makes the space as unclaimed. It changes a few bytes and can be done in a fraction of a second. If you want it to go overwrite the whole 10 GB file with 0s then it’d take the spinning hard drive about 2.5 minutes to complete the task during which time *you can’t get to anything else on the drive* without seriously slowing down the operation and whatever you wanted to do
Lots of rules were created to reflect the fact that HDDs are *slow*. A fast disk (15000 RPM Raptor drive) could do 80 MB/s but your normal bulk storage was in the 40-60 range. Modern discs with 4 or 6 ultra high density platters can do better but still rarely more than about 120 MB/s. Having to go through and erase a sector would have been a massive waste of time for no gain, anyone who cared about data destruction had an electromagnet to take care of that.
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