On Friday 04 August 2006 15:41, Leendert Meyer wrote:

The really paranoid people would do this:

shred -x /dev/hdx

I did that once with a USB-pendrive. See "man shred" for an explanation.

Hi Leen, I realize you suggested he read the man page for shred, but since this disclaimer is well towards the bottom, it bears emphasizing: CAUTION: Note that shred relies on a very important assumption: that the file system overwrites data in place. This is the traditional way to do things, but many modern file system designs do not satisfy this assumption. The following are examples of file systems on which shred is not effective: * log-structured or journaled file systems, such as those supplied with AIX and Solaris (and JFS, ReiserFS, XFS, Ext3, etc.) regards, Carl

On 8/4/06, jdd sur free wrote:

be aware also that HD heads are floating and do not always write at the same place, so its possible to read data on a disk many times after it have been erased whatever system you use (of course it needs much and expensive efforts)

so the only effective mean to delete data is a big hammer :-)

jdd

I would really like to see a definative article from the last 7 or 8 years that supported the above contention. I know about the often referenced 1995 Gutmann paper. He basically said that a lot of drives made in the 80s were so low density and non-precision it was very hard to "wipe" those without lots of passes. That early 90's drives were more dense and more precise and thus easier to wipe with a few passes, but that drives coming on the market in the mid 1990s were so dense and precise and were using multi-bit encoding techniques that he could not envision any data recovery after even a single pass with that class of drive. Unfortunately, I have not seen any whitepaper etc. that discusses data recovery from newer generation drives. ie. anything 4GB or larger probably is too new to be covered by the Gutman paper. Greg -- Greg Freemyer The Norcross Group Forensics for the 21st Century

On Friday 04 August 2006 14:29, Leendert Meyer wrote:

On Friday 04 August 2006 21:49, Carl Hartung wrote:

...

On Friday 04 August 2006 15:41, Leendert Meyer wrote:

...

The really paranoid people would do this:

shred -x /dev/hdx

I did that once with a USB-pendrive. See "man shred" for an explanation.

Hi Leen,

I realize you suggested he read the man page for shred, but since this disclaimer is well towards the bottom, it bears emphasizing:

CAUTION: Note that shred relies on a very important assumption: that the file system overwrites data in place. This is the traditional way to do things, but many modern file system designs do not satisfy this assumption. The following are examples of file systems on which shred is not effective:

* log-structured or journaled file systems, such as those supplied with

AIX and Solaris (and JFS, ReiserFS, XFS, Ext3, etc.)

Of course you're quite right. But /dev/hdx does not refer to a file system, but to the whole (unmounted) disk. So if shred is used that way (/dev/hdx), I can't share your worries. :)

And, after reading jdd's post, better to /physically/ shred the drive /too/.

Cheers,

Leen

On 8/3/06, Per Jessen wrote:

...

Unmount the partition and run fdisk /dev/hdx, type m for help there and delete all the partitions you want to wipe out and create a new partition on top of that.

That doesn't actually erase any data, FYI. As others have said, to erase the disk and prevent most data-recovery attempts, you need to write something to each and every track using 'dd'.

Yes, that was the quickest solution to prevent casual attempt to read the data from the disk, for the paranoid, dd would be the better option.