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Date: Fri, 3 Dec 2010 11:41:57 +0100
From: Anatolij Gustschin <agust@denx.de>
To: dedekind1@gmail.com
Subject: Re: UBIFS partition on NOR flash not mountable after power cut test
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On Fri, 03 Dec 2010 12:28:05 +0200
Artem Bityutskiy <dedekind1@gmail.com> wrote:

> On Fri, 2010-12-03 at 11:07 +0100, Anatolij Gustschin wrote:
> > UBI: scrubbed PEB 149 (LEB 0:19), data moved to PEB 40
> > 
> > My question is: should this PEB really be preserved? I think, no.
> > It was prepared for erasure and would be entirely erased if no
> > interruption would occur.
> 
> Well, in general, my thinking is, if only the EC header is corrupted, we
> do not know why - may be this was just because of some bit-flips or
> radiation, and UBI better preserves it, just in case. I mean, there is a
> risk to destroy useful data otherwise.
> 
> Then the upper layer SW like UBIFS should know what it was erasing, and
> should re-issue the erasure. This is also a requirement made by the
> "unstable bits" problem Matthiew found on NAND, and challenged me with.
> 
> To put is simple: I think it is saver for UBI to preserve it. Upper
> layers will erase it again if it is not needed.

OK, thanks for the clarification!

Anatolij