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Old 05-22-2009, 11:18 AM   #11
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Once the item is deleted, the computer marks its spot on the drive as available, and begins to overwrite it with new data. What can still be recovered are just pieces of the old item.
In your example, both files filled the available space on the drive, so there probably wouldn't be much to recover from the old file. A 1 gig drive with a 1 gig photo uses up the entire drive. Deleting it and saving a NEW 1 gig file would use up all the space, effectively (I think) overwriting the deleted file.

Think of it this way....
Say that the file on your drive is a 400 page book. When you delete it, the computer starts to overwrite the book. So when you go to recover the deleted file,
you might only get page 32, pages 100-111, page 45, half of page 333, and pages 298-322, plus the third line from page 2 and 12 words from pages 334 and 4 words from page 400.
Once a bit of info has been overwritten, it is gone, but the parts not yet overwritten are still recoverable.

As I understand it, anyway.
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Old 05-22-2009, 11:21 AM   #12
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I understand it completely differently GF. The erasing programs that effectively erase your hard drive completely do so by over writing the data with other data many many many times. If what you were saying were true then you would only need to over write the data one time completely and then the original data would be gone forever. This is not true though. Even after the entire drive has be over written, even 3 or 4 times lets say, someone who knows how can still recover some if not all of the original data.
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Old 05-22-2009, 11:21 AM   #13
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Quote:
Originally Posted by Alix View Post
So...are you the REAL GB or the shadow GB today???
Only the shadow knows.
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Old 05-22-2009, 12:01 PM   #14
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Is overwritten data really unrecoverable? - Computerworld Blogs
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Old 05-22-2009, 12:14 PM   #15
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Interesting article. Thanks GF.
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Old 05-22-2009, 04:43 PM   #16
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when you erase or delete something you just make it invisable (unavailable for you to see). and info is writen over the top. like repainting a wall - the old paint is still under there. you would need to strip the old paint to completely remove the old paint. there are back ups of your data to be used for a system restore (when you can go back in time and restore info you lost by deleting it). you can do a government shred which chops and scatters the data but it is still there in peices.

to totally erase the drive and make nothing recoverable you need to write the drive to zeros which is like degaussing a video tape. thats how it has been explained to me.
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Old 05-22-2009, 05:57 PM   #17
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That is how I always understood it too msmofet, but if that is true then why do we need large drives. As you described, drives essentially have unlimited space since info is just piled on top of info. If that were really the case and information was not lost, but just invisible then theoretically we would be able to have a very small drive, but have much more info on it than you would think you could. That is not true though.
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Old 05-22-2009, 06:17 PM   #18
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Quote:
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That is how I always understood it too msmofet, but if that is true then why do we need large drives. As you described, drives essentially have unlimited space since info is just piled on top of info. If that were really the case and information was not lost, but just invisible then theoretically we would be able to have a very small drive, but have much more info on it than you would think you could. That is not true though.

GB, that would be true if you always deleted stuff and never used your hard drive to store files. No one does that. Our hard drives are loaded with stuff we keep, not discard.
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Old 05-22-2009, 06:23 PM   #19
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We delete stuff because we run out of space though Andy, so if it were true that data is never really removed from the hard drive then all we would have to do is put something on the drive then delete it. It would still be on the drive, but invisible. You could then put your next item on and delete it and on and on. Then you would only need to retrieve the file you need when you need it and then delete it again freeing up that space when you are done.

If the article that GF posted is correct then that explains that what we have always been told is not really true, which would make the most sense to me.
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Old 05-22-2009, 06:26 PM   #20
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I would have the opinion that once a drive is over written, very little if any of the original file is recoverable.
We format our drives when we dispose of them by slamming them against a concrete floor, so no data is recoverable. I'm not so sure that's the best way.
When we recycle, we have the company sign an agreement to erase the data and make it unrecoverable, it's corporate data.
We had 'very important person's hard drive' and it was not working. We ended up sending it out to recover files to the tune of $3500 with no guarantees. The disk was not revolving in it's case. The only way they could recover the data was to rebuild the case around the disk-I think that's what they did. They didn't try to recover data under written data and I could imagine that being incredibly expensive if the top copy was $3500.
If I wrote something I wanted to erase, I'd delete it and write over it. (the space)
I would defragment the disk, erase the thing I wanted erased, then over write the area and defragment it again. That's what I would do for my files.
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