Re: CFFA Card

["Michael J. Mahon" <mjmahon@aol.com>]

Scott Alfter wrote:
> In article <boucher1-58A840.11514731032009@news-wc.giganews.com>,
> Robert Boucher  <boucher1@alumni.texas.net> wrote:
>
> > Either I am too old to understand, or I am not getting across my 
> > problem. Using the CFFA card or a card reader and Ciderpress, Copy II+, 
> > Mac OS10.4, or Windows XP, when I try to format the flash card, I get a 
> > message this card cannot be formatted.
>
>
> Zeroing out the card before partitoning and formatting might get it working
> for you; it's worked for me in the past.  Under Linux, something like this:
>
> dd if=/dev/zero of=/dev/sda bs=512 count=2048
>
> would be sufficient (change sda to whatever is appropriate).  Under Mac OS
> X, the erase disk option in Disk Utility will work if you change the
> security options to "zero disk."  I'm not aware of anything built-in on
> Windows that offers similar functionality, but you can always boot Linux
> from a CD or flashstick to get the job done.

CF cards, as pointed out, implement wear=levelling algorithms that
are very effective.  Unless you are really trying to "wear out" a
card, it is quite unlikely that you will succeed in doing so, since
you would have to re-write essentially the entire capacity of the
card until it was almost all at its re-write limit.  (Any relatively
constant data on the card, like the contents of most files, will be
relocated as needed to heavily used blocks to make a fresher block
available for frequently changed data, like directory structures.)

However, this means that the card contains, in addition to its
"official" capacity, quite a few blocks for use as spares and
several that contain proprietary-format information on bad blocks,
block-usage history, etc., that cannot be restored except by a
manufacturer-provided utility.

Since these blocks are subject to updates when the card is written
to, any interruption in power during a write can result in damage
to the proprietary structures.

Almost all cards that experience a "hard" failure ("can't format")
can be revived quite easily by running the manufacturer's utility.

The usual FAT formatting routines of cameras and OSs can't restore
the proprietary data structure, and the card is "dead" without it.

-michael

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