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Date: Tue, 18 Oct 2011 17:32:36 +0200
From: Ivan Djelic <ivan.djelic@parrot.com>
To: =?utf-8?Q?Jean-S=C3=A9bastien?= Gagnon <jsgagnon@vizimax.com>
Subject: Re: UBIFS recovery fails
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On Tue, Oct 18, 2011 at 04:10:32PM +0100, Jean-S=C3=A9bastien Gagnon wrote:
> The situation you described should be already handled correctly by UBIFS,=
 if the nand driver is correctly reporting pages with bitflips with the -EU=
NCLEAN.  In this case, UBI will move the PEB to a new one as soon as possib=
le to avoid this problem.

This would be true, if you could assume that a page reading failure always
occurs after a previous read on the same page reports an ecc correction.
But this is not the case: we had several unstable pages going from 0 bitfli=
ps
(perfect read) to 2 bitflips (failed read). No way to detect any failure, no
way to scrub data before it's too late.
And the answer from the manufacturer was: you should not use any partially
programmed/erased pages anyway, those should be cleaned up after recovering
=66rom a power failure.

> My comment was really about the original error posted by Daniel Kuhn :

I agree on your comment about blank page; bitflips on erased space should be
corrected, or the upper layers should be robust to them...

BR,
--
Ivan