shredding files on a flash drive

[James Knott]

Kristian Erik Hermansen wrote:
> On Jan 26, 2008 4:45 AM, James Knott <james.knott-bJEeYj9oJeDQT0dZR+AlfA at public.gmane.org> wrote:
>   
>> Why do they have to be realigned?  The servo and clock information are
>> embedded in the signal, on each platter.  You seem to be of the optinion
>> that the data has to be aligned between platters.  This isn't so, though
>>     
>
> Well, the tracking data is written to multiple platters at the same
> time, as well as the data.  So, if you don't align the platters, you
> get junk!  I still encourage anyone to prove me wrong.  Post a youtube
> video of your success if you think it is possible :-)
>   

As I have said before, please read about how drives actually work.  Each
disk surface is written independently of the others and contains the
necessary tracking and clocking info.  In common drives, the data is
written to one track or "cylinder" until that track is full.  Then the
heads are switched to access the next surface etc.  Once all the tracks
are full in one cylinder, then the head seeks to the next cylinder.  The
clock and servo info are recovered from the disk surface every time a 
head switch takes place and the sector number verified on every read or
write operation.  This means that it's possible to take any individual
disk from the array and recover it's data.  Recovering entire files,
however, will require recovering the data from all surfaces that the
file existed on.  Also, the onus is generally on the person making the
claim to provide the proof.  You claimed it was impossible.  I have
provided evidence that it is not so, including using some of your own
evidence.  You have more than demonstrated you are arguing from a point
of ignorance, where you don't understand the fundamentals of how disk
drives work.  Please do a little research, before demanding that someone
has to prove you wrong.  As I mentioned earlier, at one point in my
career, maintaining and repairing disk drives was part of my job, so I
also have some actual hands on experience to rely on.

-- 
Use OpenOffice.org <http://www.openoffice.org>
--
The Toronto Linux Users Group.      Meetings: http://gtalug.org/
TLUG requests: Linux topics, No HTML, wrap text below 80 columns
How to UNSUBSCRIBE: http://gtalug.org/wiki/Mailing_lists