shredding files on a flash drive

[James Knott]

Kristian Erik Hermansen wrote:
> On Jan 25, 2008 11:50 AM, James Knott <james.knott-bJEeYj9oJeDQT0dZR+AlfA at public.gmane.org> wrote:
>   
>> They work with more than just deleted files.  They recover data from
>> drives with severe hardware damage.  Sometimes, such as after a fire,
>> the only recourse is to pull the platters out and mount them in a
>> similar drive.  IIRC, this was mentioned by the presenter at the TLUG
>> meeting a few years back.
>>     
>
> What you are perhaps referring to is a spin-stand.  However, you
> *cannot* separate the platters and recover the data.  The reason is
> that the tracking/data are written to multiple platters, and if minute
> misalignment occurs, you cannot determine what bit is what bit.  You
> just have garbage bits.  You also need to know the coding the drive
> uses.  This varies widely among manufacturers.  The most elegant hack
> would be to somehow replace the parts that were damaged and somehow
> keep the platters perfectly aligned when you swap them into a similar
> drive.  Then, data recovery may perhaps be possible, but not if the
> platters become misaligned (and still it is very difficult to perfect
> -- yes it is possible).  I think it is wise that you invest in reading
> the following two PDF documents this weekend from the site below.
> Still note, misaligned platters spell doom!
>
> http://www.actionfront.com/ts_whitepaper.aspx
> http://www.actionfront.com/whitepaper/Drive-Independent%20Data%20Recovery%20Ver14Alrs.pdf
> http://www.actionfront.com/whitepaper/Drive%20Independent%20Data%20Recovery%20TMRC2005%20Preprint.pdf
>
> I encourage you to read the entire articles, but if you are not
> inclined, here is a short summary.  This does not substitute for the
> wealth of information contained in those two entire documents however!
>
> ""'
>   

It would appear sections 4.1.4 and 4.2.1 cover what I was describing. 
As I mentioned in a previous note, it would take a fair amount of
effort, as described in those section.  Also, I was not referring to
over-written or erased disks.  Simply recovering data, from drives where
some part of the hardware, other than the platters, has been damaged is
what I was referring to.  Those two sections cover it nicely.  Bottom
line, it is possible to recover data after the platters have been
removed from the drives.  Also W.R.T. the "tracking data", yes it is
written on every disk, unlike the old disk pack drives where you had one
servo head, which provided tracking for the entire drive.  The data
clock is also embedded in the data, which means so long as the head can
get a decent signal, the data can be recoverd.

One thing everyone has to bear in mind, is that data recovery is a lot
more expensive than backups.

-- 
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