Patrick’s development blog

Delete data from hard drive securely

Posted in Computer Science, Security by Patrick on May 10, 2011

It’s common for people to say that it’s necessary to overwrite the hard drive many times before the data becomes unrecoverable. This is however just a myth. The probability of recovering only a single byte is less than 1%, so it’s very unlikely that someone can restore something much bigger like 100 MB.

In other words, overwriting the hard drive many times is just a waste of time. Writing 0:s on the whole hard drive is sufficient and can be done with tools like dd.

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