Re: [OM] Formatting card from computer

[Chuck Norcutt]

Thanks, I was unaware of the SD formatter.  However, after reviewing the 
content of the page you linked and the Wiki article on SD cards I am not 
at all concerned about my occasional formatting of SD cards in my 
computer.  I saw no information on either site to support the contention 
that "*regular* formatting on a computer is actually bad for SD cards". 
 What is there says that "Using generic formatting utilities may result 
in less than optimal performance for your memory cards" and also goes on 
to imply that other formatting utilities might overwrite the "protected 
area" of SD cards.  One can get less than optimal performance from an SD 
card from formatting that changes the block size of the device to 
something that's not a multiple of it native sector size.  But that 
would never happen in a simple FAT32 format.  And cards used in our 
cameras just to record their images don't make use of the "protected 
area" so I suspect overwriting it might actually increase the usable 
size of the card slightly.  I dunno.  If I had a brand new card I'd try 
it out.
I am fully aware of the wear leveling behavior that occurs on *all* 
flash memory technology cards.  The flash controller also uses ECC 
(Error Check and Correction) bits to try and verify the validity of the 
data.  Micron controllers can detect 2 bit errors and correct single bit 
errors.  But the best it can do in the case of an error involving more 
than a single bit is to return a read error and *then* mark that 
particular block as bad.  If the first write to the card is useful data 
then that data is lost.  I'd prefer that the first error that's returned 
is just formatting data.  Maybe overkill on my part but my single 
instance reformatting on Windows is not going to damage it and may even 
be useful.
Chuck Norcutt


On 12/27/2014 10:24 PM, Moose wrote:
> On 12/27/2014 6:34 PM, Chuck Norcutt wrote:
> > <snip lots of useful stuff>  If there are errors these will be noted
> > and the defective areas marked so as not to use them in the future.
> > The first time I ever use any drive or flash card I format it in the
> > computer first and do a normal format to test and verify it.
> I don't think this is of use with an SD card. The card has its own
> internal controller, which remaps physical memory to what it shows the
> outside world. It's supposed to both map out bad locations, as they
> develop, and level usage, so that 'wear' is evenly distributed.
>
> This is all to deal with the fact that the memory has a limited number
> of read/write cycles before starting to produce errors. I think it makes
> a full, conventional computer based format meaningless.
>
> Also, the SD Association says that regular formatting on a computer is
> actually bad for SD cards, and offers a free formatting utility that I
> have on my computers. <https://www.sdcard.org/downloads/formatter_4/>
>
> But basically, I just format in the cameras, if I remember to when the
> card is new, and when I reuse a card.
>
> > But if it to be used in a camera the camera should be allowed to
> > reformat it before its used since the camera ads some data of its own
> > such as a few fixed name file folders.
> They seem to create those anyway, in my admittedly limited experience
> with Canon, Oly and Panny cameras.
>
> What A. Card Moose
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