Deleting Doesn't Mean It's Deleted

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Deleting Doesn't Mean It's Deleted

Postby Spark » Sat May 22, 2010 8:23 pm

This pertains to a PC with XP:

I know this has been covered in part here before but there is somethings that have not been explained.

When a file or folder is deleted you are only removing the reference to it and that all though the file seems to have been deleted it actually has not.

Even reformatting the HDD does not remove these previously deleted files and folders I have read.

My question here is:

Say the HDD is 200gb in size and it has 150gb of files and folders on it and then they are all deleted and then the HDD is reformatted with a clean reinstall of the O.S. and now the HDD shows that it has all this new space on it less what was used for the O.S. If all this is correct where are all these files and folders that were deleted that are supposed to still exists?

The only way to make previously stored HDD files and folders unreadable is to make multiple rewrite passes over it with a shredder utility or to burn the platters in a fireplace that are inside the HDD.

Edit:

If a file or folder is sent to the Recycle Bin then it falls into the above category, but if a file or folder that is deleted (shift key then delete key) by passes the Recycle Bin then it does not and it is gone for good. Any truth to this ?

Can you use a file shredder utility like you would use a Recycle Bin ?
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Postby Mr T » Sat May 22, 2010 9:56 pm

No, you can recover the data still... When data is deleted the os removes the first letter or number of the name and replaces it with a symbol, security feature so it can be 'undeleted' if needed... When I recon old hard drives, I run them through a machine that writes 0's to every sector. 1 pass and you can still recover... The machine I use can do 3 passes and you can still recover enough data to build a picture of what is on the drive, but you'd need decent software to do it (ie pay for it)...

Some drives, you can burn, run magnets over, attack with seawater and still recover data off it... The only true way to destroy the data is smash the drive platters...
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Postby Spark » Sun May 23, 2010 3:40 am

Mr T wrote:No, you can recover the data still... When data is deleted the os removes the first letter or number of the name and replaces it with a symbol, security feature so it can be 'undeleted' if needed... When I recon old hard drives, I run them through a machine that writes 0's to every sector. 1 pass and you can still recover... The machine I use can do 3 passes and you can still recover enough data to build a picture of what is on the drive, but you'd need decent software to do it (ie pay for it)...

Some drives, you can burn, run magnets over, attack with seawater and still recover data off it... The only true way to destroy the data is smash the drive platters...


I understand what you said for the most part, but like in my example above, if a 200gb HDD has only 50gb of free space left on it (150gb used), why is it that after reformatting it you reclaim much of what had been used? How is it that 150gb of old previous files or folders are still (hidden) on the HDD when after reformatting the HDD used space is reclaimed. How does a 200gb HDD hold 350gb of data? This is the part that I don't understand.
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Postby Copper » Sun May 23, 2010 4:24 am

all file and folders locations is store in the registry, when you delete a folder or file , the registry entry is deleted, not the folder or files, thus windows see it as free space, and when windows needs to use the space, it simply writes over whats there
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Postby hunter1801 » Sun May 23, 2010 10:32 am

I would wonder the same things you are a while ago. It's a confusing concept to think about, but I think I've figured it out for myself though. Basically you shouldn't consider it "deleting", think of it in terms of what is actually happening, which is what Mr. T described. When something is deleted, its name is altered so that the computer no longer references it. It doesn't get rid of anything, it just makes it "irrelevant". If you fill your HD up 200/200gigs then wipe everything, you'll be back at 0. This doesn't mean it is "empty". Everything is technically still there, but since it was all made "irrelevant", the computer doesn't register it. So your computer shows 0/200gigs used.

As far as filling up a 200gb HD with 35bgb, I've never heard of that. You'll never be at 350/200 as far as I know. If you are referring to what you were talking about before as far as PREVIOUS files still being on there. Sure technically you could fill a drive over and over again and be at 1,000gb/200gb, but since most of the files have been made "irrelevant", it won't show that like I described above.

So basically, don't think of it in terms of space being filled up or emptied. All data is is numbers. Think of it in terms of what you are telling your computer to "remember keep this" or "forget about and don't bother showing this on my computer" in a way.
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Postby Karlsweldt » Sun May 23, 2010 2:10 pm

When a file is to be erased, the first character of the file name is changed to an "E5" bit. This causes it to become hidden from view, and also sends it to the 'recycle bin' for future restoration or disposal. But regardless of how many times you do an unconditional format on a hard drive, those files may still be available for recovery.. unless you use two basic format modes, repeating the sequence no less than 5 times. The first format would be in "0" type, then the second would be in "1" type. You could also use an obscure "F" format mode, to further ensure the files are 99% gone. By default, formatting a hard drive will keep those hidden and system files in a 'mirror' image for the possibility of recovery.
A small program called Killdata will do for most non-sensitive data. But a "secure" erasure as per DoD rules entails a bit more work.
However.. if you plan on the drive never being used again, then a degaussing coil (as used for CRT monitors) or a bulk-tape eraser will do the job in less than 15 seconds! Modern hard drives have no mechanical means to "track" the data sectors, as older drives did. It is all electronic, and with no "tracks" to find, the disks are useless. Of course, a 3-lb. maul would also do a nice and quick but messy job.
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Postby AmEv » Mon May 24, 2010 6:31 am

Not even the feds could recover data! :lol:

Karl, was this what you were talking about?

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Postby Karlsweldt » Mon May 24, 2010 4:15 pm

AmEv wrote:Not even the feds could recover data! :lol:

Karl, was this what you were talking about?

Image


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Err. yeah, that would do it, surely! But why swat a gnat with a guitar?
This 'toon is probably over the edge, too!

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