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Spørsmålet
SuperUser leser cantsay ønsker å vite hvorfor data kan gjenopprettes etter formatering:
If a quick format just marks bits as writable and a normal format writes zeroes to the entire disk, why do people bother with DBAN and why are multiple passes ever required?
Hvorfor kan data gjenopprettes etter formatering?
Svaret
SuperUser-bidragsyter Alex McKenzie har svaret for oss:
It used to be possible by reading the residual magnetism left by the previous bits. This is not so much of an issue now that the tracks and bits that hard-drives write are so small. It is almost impossible to recover any meaningful data off of a zeroed drive with modern disks.
This next section is only true for Windows XP (as Psycogeek pointed out, Vista and later Windows systems do zero out the hard-drive if you do a full format).
That being said, your definitions of quick format and normal format are off. A normal format does not zero out the disk, that would take too long. The difference between the two is that a normal format looks for bad sectors on a drive while a quick format does not.
So it is best to use a tool like DBAN to do at least one pass if you want to make sure data is not recoverable. And if you are doing one pass, then why not do a few more just for fun?
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