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Old 05-22-2009, 06:35 PM   #21
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Originally Posted by blissful View Post
I would have the opinion that once a drive is over written, very little if any of the original file is recoverable.
then why do you always hear about the police getting hold of hard drives and recovering information that was supposedly erased? Maybe that really does not happen as much as I think it does. Perhaps I am confusing TV with real life.
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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.
I do the same thing. I then take a hammer to it and go to town. It might not be the best way, but I am confident that it is enough so that someone would need to have a real reason to try to get any info and since my most sensitive data is my baning info and I am far from rich I doubt anyone would go through any real effort to try to get my data after I smash the drive to bits.
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Old 05-22-2009, 06:45 PM   #22
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then why do you always hear about the police getting hold of hard drives and recovering information that was supposedly erased? Maybe that really does not happen as much as I think it does. Perhaps I am confusing TV with real life.
I think the police and detectives WANT you to believe they CAN recover whatever, about whatever. If a person deletes something, it's recoverable if it isn't overwritten. Which is why I think a person needs to make sure it's over written if they want it erased. There's a BUNCH of bravado with authoritarian type police and detectives, that they have SO much power or knowledge--oh yeah. And there is so much they don't know, like in my state their driving, criminal, divorce etc records are on an online database, so you can look it up, as an average citizen. It makes them crazy, they think you know because you are stalking them...lol. They like to 'talk' a lot, it makes them crazy. Crazy people with guns, how cool is that? Versus average people w/ or w/o out. Don't ask me how I know.I'd be a good asset to a detective force needing IT help.
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Old 05-22-2009, 07:08 PM   #23
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GB--

A hard drives files if simply erased and removed from the trash bin can still be easily recovered if all the sectors occupied have not been overwritten. This is done using a compression algorithm known as lossy compression--the parts of the file not available are predictable to a high degree by the pattern that is left. The scenario you describe is somewhat different, i.e. the writing of a file of exactly the same size in the same space. It is a lot trickier, but files pieces do not use every bit in every cluster. Even if eash and every bit, however, is overwritten, there is a residual magnetic charge left from the old image. It is sometimes called a palimpsest, which derives from the time when writing material was very expensive. When the usefulness of the document was over, it would be scraped clean and reused, but it was still possible to rescrape it and recover what had been underneath. Similarly, data written on magnetic media over other data can be "scraped" off to allow access to what underlies it. This can be done because the magnetic particles that are used to store binary data have a memory once written to. It is possible, though expensive and tedious, to go back two or three iterations of data written and overwritten. The only--so far--reliable method of completely erasing data from magnetic media such as hard drives is to write a bit-wise pattern of zeroes many times, effectively reducing the magnetic residual memory to an unusable state. The hammer method would not deter a determined tech with enough funding and at least most of the pieces. Hope that helps! (BTW, just what are you trying to erase? )
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Old 05-22-2009, 07:44 PM   #24
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like i said you need to write the drive to zeros to completely erase the drive. without the 1's there is no info.
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Old 05-22-2009, 07:51 PM   #25
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like i said you need to write the drive to zeros to completely erase the drive. without the 1's there is no info.
Yes, but you need to do it several times, at least.
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Old 05-22-2009, 07:53 PM   #26
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You need larger hard drives for a number of reasons:
  1. Microsoft Windows is sloppy, and accumulates junk which slowly takes up additional disk space.
  2. As hard drives have gotten bigger, applications and data have also gotten bigger.
  3. Users accumulate more "stuff" on their hard drives (e.g. pictures, video clips).
As previously stated, when you delete a file, it's not immediately gone. It is simply removed from the file allocation table. That means if you hit delete the second before the cops kick in the door, you're sunk. If you deleted it months ago, the chances are much lower that the data can be recovered.
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Old 05-22-2009, 07:54 PM   #27
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Yes, but you need to do it several times, at least.
I you write zeros over every bit on the hard drive (just one time), what could possibly be left to recover?
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Old 05-22-2009, 08:03 PM   #28
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I you write zeros over every bit on the hard drive (just one time), what could possibly be left to recover?
there isn't anything to recover. zeros are zeros. the drive can't read just zeros it needs the ones also, thats what makes it readable.
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Old 05-22-2009, 08:03 PM   #29
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I you write zeros over every bit on the hard drive (just one time), what could possibly be left to recover?
To even the casual geek, nothing. I have, however, recovered data from hard drives that have been low level formatted (theoretically returned to the factory state), partitioned in a different way, and populated with new data. It's all a matter of how much time you can spend. For the why, see my first post in this thread.
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Old 05-22-2009, 08:19 PM   #30
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GB--

A hard drives files if simply erased and removed from the trash bin can still be easily recovered if all the sectors occupied have not been overwritten. This is done using a compression algorithm known as lossy compression--the parts of the file not available are predictable to a high degree by the pattern that is left. The scenario you describe is somewhat different, i.e. the writing of a file of exactly the same size in the same space. It is a lot trickier, but files pieces do not use every bit in every cluster. Even if eash and every bit, however, is overwritten, there is a residual magnetic charge left from the old image. It is sometimes called a palimpsest, which derives from the time when writing material was very expensive. When the usefulness of the document was over, it would be scraped clean and reused, but it was still possible to rescrape it and recover what had been underneath. Similarly, data written on magnetic media over other data can be "scraped" off to allow access to what underlies it. This can be done because the magnetic particles that are used to store binary data have a memory once written to. It is possible, though expensive and tedious, to go back two or three iterations of data written and overwritten. The only--so far--reliable method of completely erasing data from magnetic media such as hard drives is to write a bit-wise pattern of zeroes many times, effectively reducing the magnetic residual memory to an unusable state. The hammer method would not deter a determined tech with enough funding and at least most of the pieces. Hope that helps! (BTW, just what are you trying to erase? )
Thanks bullseye. This actually helps a lot. So basically, often times the data is still really able to be recovered, but it is cost prohibitive.
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