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In today's article we deal with the deletion of data. Sometimes you get to have a huge amount of discs, accumulated over the years, which were once (not anymore) that now have no reason to exist in our drawer. Okay that storage space is never too, but drives off in a drawer I have never served very. This guide will be useful to all those who are going to sell a record, but do not trust to the end because the user to whom you sell may obtain your personal information.

At this point we must make a necessary clarification.

When we format a disk or partition that we format the data is not deleted, are only labeled as “overwritten“. In this way the first new data that will save on the formatted disk overwrite the old data and there will be noticed nothing. By the time we sell a formatted disk who buys it can overwrite the old data, but can also use a program like “foremost” to retrieve data and damaged partitions, potentially coming to save us from all the content formatted (personal files, the password, etc..).

Essitono But fortunately for us, some programs that not only format the drive, but even overwrite the deleted data with a beautiful “zero”, making it impossible to recover the data deleted. The program that we use today is “dd“, and is contained in the main distributions (and in all the live distro forensic).

The operation is quite simple:

dd if=/dev/zero bs=xxxx of=/dev/hda1

Setting the virtual device “/dev/zero“, dd writes on the disk the 0x00 pattern from the first to the last sector of the disk.

The parameter “bs” should be set depending on the size of the disc (this is. “bs=8192“, “bs=16384“, etc..).

Alternatively, you can use “dcfldd” in place of “dd“, the difference is that we will follow the prograssione work in real time.

dcfldd if = / dev / zero bs = 4096 of = / dev / hda

When the work we can control the actual device overwriting.

dd if=/dev/hda | xdd | grep-v "0000 0000 0000 0000 0000 0000 0000 0000”


xxd -a /dev/hda

In both cases, the output should be a more or less long sequence of zeros.

0000000: 0000 0000 0000 0000 0000 0000 0000 0000 …………


6216ff0: 0000 0000 0000 0000 0000 0000 0000 0000 …………

So from now on no more trouble if we have to sell a record. With these tools, we have the assurance that the data can never be retrieved. Remember to make backup copies if the data we need.


I keep this blog as a hobby by 2009. I am passionate about graphic, technology, software Open Source. Among my articles will be easy to find music, and some personal thoughts, but I prefer the direct line of the blog mainly to technology. For more information contact me.


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