Re: [patch] Allow any filesystem on MTD Nand when Read Only

Pantelis Antoniou
2004-05-06T09:58:20Z

Thomas Gleixner wrote:

>On Thursday 06 May 2004 11:30, Srinivasu.Vaduguri@nokia.com wrote:
>
>>>How many times have you written the block in order for something like
>>>this to occur?
>>>
>>I haven't counted the number of times. But I remember reading some
>>information, that even on multiple reads we do get bit errors and it is a
>>symptom that the block slowly becoming bad after some time.
>>
>
>Hmm. Never seen this. I have some read only paritions which are accessed in
>stress testing and I never have seen, that a block gets bad due to reading.
>
>
>>But what I feel is, a read-only filesystem like cramfs is not that reliable
>>on NAND flash. We have to detect a bad block early.
>>
>
>Yep, but you can only detect it while writing / erasing.
>
>
Actually when using ECC you *CAN* detect a single bit error.
You could use this information as a trigger to migrate the block
and then mark it bad immediately.

However it better be only one bit that flipped because if more
bits are gone you're screwed.

Regards

Pantelis