So i was enjoying some down time for myself the other night taking a nice warm bath and letting my mind wander when i suddenly recalled a time when i worked at a research station and some idiot managed to somehow delete over 3000 excel spreadsheets worth of recently collected data. I was charged with recovering the data and scanning through everything to make sure it was ok and nothing deleted…must have spent nearly 2 weeks scanning through endless pages…and it just barely dawned on me to wonder…exactly…how the hell do data recovery tools collect “lost data”???
I get like a general idea of like how as long as like that “save location” isnt written over with new data, then technically that data is still…there???? I…thats as much as i understand.
Thanks much appreciated!
And for those wondering, it wasnt me, it was my first week on the job as the only SRA for that station and the person charged with training me for the day…i literally watched him highlight all the data, right click, and click delete on the data and then ask “where’d it all go?!?”
In: Technology
Most answers seem to forget that even writing over a file it might still be recoverable (on a hdd at least). I’ll try to ELI5 this one:
Your hdd is like a stack of sheets of papers, and you write on them using pencils. And given you are writing and reading all the time, in the interest of time, when something has to be deleted, first you just remove that sheet from the stack to a “to be recycled” stack.
When you run out of paper (or earlier, if you fancy it) you may get a sheet back from the recycle stack. Before you write, you use your eraser.
Now, at first you can probably still read (some of) the previous text on the sheet. But after recycling it a few times, it will be unreadable.
A few tools (called a shredder) will rewrite and erase over the sheet multiple times until the text you had there becomes unreadable.
Ah, formatting usually don’t destroy data as well.
(to add to this metaphor a bit: pages are numbered, and you try to write sequentially, but then you delete something from the middle of the stack. When you need more space, you reuse that, but a sheet isn’t enough for what you are writing, so you make a note on the bottom, “next page: 10”, so when reading you move back and forth because the text is *fragmented* across many pages. De fragging is about reorganizing the sheets so that you don’t need to jump around so much.)
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