Archived from groups: comp.sys.ibm.pc.hardware.storage (
More info?)
Previously alex <alexx9@iname.com> wrote:
> Arno Wagner <me@privacy.net> wrote:
>>Does not need an application, I am a Linux user. The task is close
>>to trivial from a technological point of view.
>>All the following will work fine (hdb is the target) :
>>
>>cat /dev/zero > /dev/hdb
>>dd if=/dev/zero of=/dev/hdb
>>dd_rescue /dev/zero /dev/hdb
> will have to try this one...
> tnx.
Works well. I have been using this for a decade now.
>>> VOGON seems to disagree with you.
>>
>>Have a reference for that? I am not about to conduct a field
>>test, but c't did an anonymous one last year: They claimed to have
>>accidentally overwritten a very important file on a current HDD
>>and whether they could have it _please_ recoverd? They contacted
>>several major data-recovery outfits and all said they could
>>not do that type of job.
> Well, no first hand experience, but from what I hear they are quite
> good...
> Of course, it is just a sales pitch, but anyway:
> Case Studies
> If there is any DATA, anywhere ON your DISK or TAPE, it can be
> RECOVERED. In short, our expertise is your reassurance: your data is
> in the safest hands, anywhere.
O.K. I have no issue with that. They don't claim to be able to
recover data that is not there. The problem with overwritten
data is that it is not there in a pretty strong sense.
Also a though experiment: If you have on layer of good data
and one layer of overwritten data below that and you can
read both (albeit the second one with dificulties), then
the HDD surface is able to hold at least twice the amount
of data than the advertised capacity. The same argument holds
with multiple overwrites.
My impression is that in recent years the limiting factor for
HDD capacity was not heads or electronics but the surface
covering which can take only so many bits in a specific
area before they start to bleed into each other.
Tape and floppies are different. The recording density
is not close to the material limit there. A 1.44MB floppy
can hold up to 20MB with speacial servos and possibly more.
Arno
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