[NTLK] Storage card specifications

Dan dan at dbdigitalweb.com
Fri Apr 8 14:24:31 EDT 2011

Interesting, sounds like Flash memory's 'dirty little secret'.  Recently
on this list there was a discussion how a Newton "never forgets".  I
have a newt with data over 10 years old and everything is still there
and the data has not been touched for that long (or approximately).  Of
course everything is backed up as well, but still very interesting.  I
will definitely research this further.

We all know about magnetic based drives, the data can eventually fade.
Flash can as well.  Sounds like the longer term solution is CD/DVD,
however over the years there has been discussion on how long they truly
will last.  And the earlier CD's most likely won't due to the early
techniques.  Most of the better quality CD/DVD's now say 100 years life
(at least).  But then again how to prove that and a company just could
be making those promises thinking they won't be around in 100 years.

Another consideration, the data storage formats change over the years.
Records, tape, CDs, Flash etc and we all know that record players are
not as easy to come by these days.  It is likely that the data will be
moved over to a new medium long before the medium itself fails.
Especially since it becomes easier to move great quantities of data
quickly as technologies improve.


On 4/8/2011 3:16 AM, Bradley Loeding wrote:
> Unfortunately, Flash will eventually lose its data just sitting in a drawer.
> Sad but true. The information is stored, not physically, but as trapped
> electrons whose presence or lack thereof on each cell's floating gate
> determines the logical state of the bit.
> Just as you can tunnel electrons onto the gate quickly at elevated
> potentials, so too do they slowly leak away. This is a quantum effect and is
> temperature dependent, among other things. You'll get a wide opinion as to
> how long it will take before enough of the buggers shuffle off and drop each
> cell below sense threshold.
> www.cl.cam.ac.uk/~sps32/*Data*Rem_CHES2005.pdf
> (2nd page)
> One major flash manufacture specs its passive data retention at only a
> decade. Some chip fabs claim 50-100 years, which is a bit hard to believe.
> Truth is, no one really knows, but I'd personally get a bit nervous after
> 15-20 years.
> Ironically, we can store the Library of Congress many times over on a single
> drive, yet the next generation won't be able to read it without active
> maintenance of the data... If anyone wants true long-term storage, break out
> the pen and ink.
> -Bradley

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