Wear-leveling peculiarities

[Johannes Bauer]

Am 18.05.2015 22:47, schrieb Richard Weinberger:

>>> I suspect that your threshold was never reached.
>> 
>> Yes, I suspect you're right here.
> 
> If you did not set CONFIG_MTD_UBI_WL_THRESHOLD it is 4096.
> So, regular wear-leveling did never happen.

Your initial assessment was correct. The WL_THRESHOLD is at 4096 when we 
should have configured it to a lower value for our NAND flash.

> The OOB-Data does not matter. UBI is not using OOB.
> 
> So, you have to figure out why UBIFS is dying. Maybe it is a NAND 
> issue.

Yes, sorry, I meant the EC header metadata. Indeed it looks like our 
NAND flash is dying because WL is not active. Determining the amount of 
erase-cycles of dead NAND blocks is difficult (since the EC header 
meatdata is lost as well when the whole block doesn't respond anymore).

Thank you for getting me on the right track.
Best regards,
Johannes