Joel Rees joel.rees at
Sat Dec 2 23:49:22 UTC 2017

Fear mongering?

2017/12/03 1:00 "Xen" <list at>:
> Ralf Mardorf schreef op 02-12-2017 16:23:
>> On Sat, 02 Dec 2017 12:48:39 +0100, Xen wrote:
>>> Ralf Mardorf schreef op 02-12-2017 9:31:
>>>> 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.
>>> If I recall correctly the next piece says that this only applies to
>>> Ext3/4 when journal mode is DATA, which is not the default ;-).
>> While this is correct, it's still worth to mention it.
>>> Thank you for creating noise ;-).
>> I wouldn't call such a notice noise. This notice - incompletely quoting
>> the manpage - is indeed biased, but since I provided the pointer to the
>> extraction of the manpage, the reader is free to read the complete
>> manpage. Just mentioning that the history could be shred without giving
>> a hint to pitfalls, is much more biased and furthermore it's dangerous.
> If you hadn't made a biased statement, I would not have had an issue.
> Because then you don't create the impression that this is a very serious
problem, when it isn't.
> Creating fear in people for no reason, why do you do that?

If you are doing things that your local version of the NSA has interest in
(or your local organized crime guys), for the cost of a scanning electron
microscope and a bit of time, all sorts of things are recoverable.

And hardware itself tends to have the ability to move sectors, segments,
etc., for a variety of reasons without notification, so scanning electron
microscopes often do not need to be resorted to. Just bypass the high-level
controller hardware.

Unless your OS has a reliable shred call and your hardware has a reliable
shred command, you really shouldn't depend too much on shredding.

Joel Rees
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