What would cause large block of NAND to be marked as bad?

What would cause large block of NAND to be marked as bad?

[Subodh Nijsure]

Hello,

I am working with some prototype hardware and I have seen some weird 
behaviour when testing power cut.

On my board I have Micron MT29F2G08ABAEAH4 part and now have three 
boards on which close to 20-30 blocks have been marked as bad.

We mainly run UBIFS on these boards, if there was flash data corruption 
we expected to see errors at UBIFS level i.e. not able to mount UBIFS 
file system but we didn't expect NAND blocks themselves to be marked as 
bad, due to power cut.

What would cause large number of NAND blocks to be marked as bad, due to 
power cut?

-Subodh

Re: What would cause large block of NAND to be marked as bad?

[Artem Bityutskiy]

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On Mon, 2012-05-07 at 11:05 -0700, Subodh Nijsure wrote:
> Hello,
> 
> I am working with some prototype hardware and I have seen some weird 
> behaviour when testing power cut.
> 
> On my board I have Micron MT29F2G08ABAEAH4 part and now have three 
> boards on which close to 20-30 blocks have been marked as bad.
> 
> We mainly run UBIFS on these boards, if there was flash data corruption 
> we expected to see errors at UBIFS level i.e. not able to mount UBIFS 
> file system but we didn't expect NAND blocks themselves to be marked as 
> bad, due to power cut.
> 
> What would cause large number of NAND blocks to be marked as bad, due to 
> power cut?

Did you look at Mike Dunn's bitflip_threshold stuff? It is in my
l2-mtd.git tree. Look at this patch and the next ones from Mike:

http://git.infradead.org/users/dedekind/l2-mtd.git/commit/be1bb4ef1f98059f9d54623f3ed01423095fa967

Commit messages contain descriptions and references. May be for your
flash you need to set higher threshold?

-- 
Best Regards,
Artem Bityutskiy

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