Re: Reformat Sd-Card?




"Werner Ruotsalainen [MS MVP - Mobile Devices]" <here@xxxxxxxxx> wrote in
message news:%23d7INDZTGHA.1576@xxxxxxxxxxxxxxxxxxxxxxx


BTW, I've done quite a lot of work with SmartCards (even programmed them).



Same here. Smartcards ( biometrics and otherwise), some other security
stuff with various memory configurations. Suffice it to say that cards are
not hard drives and should not be treated as such.

xTenn Wrote:

An SD card's memory has a limited number of times that it can be used and
rewritten. To get around this limitation the card uses different areas
of its memory at different times, greatly extending the life of the
memory cycles to the point that it is quite practical. But it is not
always a contigous block.

That's not really correct. There is no such 'magic' in the flash
controller. It just makes sure it maps out the useless bits (in general, in
4-8 bytes at once);


I do believe that the controllers "spread out" the writes over the sectors
of the card, arrange as effective erase blocks. The card will even turn off
various sectors as the lifetime increases (but we are talking after a LOT of
use). Here are some links to back this up:

http://www.acscontrol.com/knowledgebase/article.asp?CatID=2&ID=7
http://www.sandisk.com/Assets/File/OEM/ApplicationNotes/CompactFlash/AppNoteCFHostv1.0.pdf
http://www.kingston.com/products/DMTechGuide.pdf
http://www.robgalbraith.com/bins/multi_page.asp?cid=6007

May not be the case, but that is my understanding. No big deal either way.
:)








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