NAND read errors, R/O FS

[Steve Finney]

>On Wed, 10 May 2006 15:20:44 +0400, Vitaly Wool wrote:
>> Josh Boyer wrote:
>>
>> >Not quite the case.  You need bad block skipping, yes.  But NAND can
>> >get bit flips in good blocks still.  How do you deal with that?  You
>> >can't leave the block in that state forever because it will continue
>> >to get bit flips and then your data will be unusable.
>> Yep, I know about the issue. The recommended way to go here AFAIK is to 
>> mark the block as bad and copy its contents to a free one.

FWIW, on the Samsung K9F* NAND chip, the explicitly recommended procedure
for single bit read errors is to do single bit Error Correction (assuming ECC 
is implemented) and to NOT remap (you _are_ supposed to  remap and
copy one write errors). Apparently the chances of a 2nd bit error within a single
512 byte page (the ECC unit) are negligible.

sf