[Yaffs] bit error rates]

[Claudio Lanconelli]

Jon Masters wrote:

>On 2/9/06, Claudio Lanconelli <lanconelli.claudio at eptar.com> wrote:
>
>  
>
>>In case of ECC error fixed during read, erase the block and write it
>>again with the same data and read verification, if the ECC still fails retire the
>>block.
>>    
>>
>
>I think that's a bad idea. The block should be marked as bad. It's not
>worth losing data just to save out on theorectically marking a good
>block bad - it doesn't seem to happen in practice. I'd rather lose all
>of the good blocks than lose any data, so would many other people.
>  
>
But if you loose ALL good blocks you loose also your data!  ;-)

>  
>
>>That's because Toshiba document says about soft errors: "This condition
>>is cleared by a block erase".
>>    
>>
>
>Sure. But it might be indicative of a problem nonetheless.
>  
>
Is this statement based on any documentation or on your personal experience?
Toshiba document says also "Although random bit errors may occur during use,
this does not necessarily mean that a block is bad"
However if this is not true can you point me to other documentation 
talking about
the relationship between random bit errors and permanent block failures?

Sorry, I don't want to raise a flame war, I just want to understand 
YAFFS bad block
marking policy, and if there is a better solution.
Excuse me for my English, it's not my natural language.

Cheers,
Claudio Lanconelli