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Date: Tue, 17 Jan 2012 11:19:19 +0000
From: Angus CLARK <angus.clark@st.com>
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Subject: Re: [PATCH v3 0/6] NAND BBM + BBT updates
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Cc: Dan Carpenter <error27@gmail.com>, Kulikov Vasiliy <segooon@gmail.com>,
 Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
 Nicolas Ferre <nicolas.ferre@atmel.com>,
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 Peter Wippich <pewi@gw-instruments.de>, Gabor Juhos <juhosg@openwrt.org>,
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 Mike Frysinger <vapier@gentoo.org>, Arnd Bergmann <arnd@arndb.de>,
 Lei Wen <leiwen@marvell.com>, Sascha Hauer <s.hauer@pengutronix.de>,
 Artem Bityutskiy <artem.bityutskiy@intel.com>,
 Florian Fainelli <florian@openwrt.org>,
 Adrian Hunter <adrian.hunter@intel.com>,
 Matthieu CASTET <matthieu.castet@parrot.com>,
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On 01/13/2012 10:36 PM, Artem Bityutskiy wrote:
> On Thu, 2012-01-12 at 10:09 +0100, Sebastian Andrzej Siewior wrote:
>>
>> so the OOB array is by design more reliable than the data area?
> 
> I think so, because it is distributed, and it is historically the way
> blocks had been marked as bad, and I thing vendors make sure this
> mechanism works.
> 

Is this really true?  I was under the impression that the OOB area was the same
as the data area, as far as reliability is concerned, and is subject to the same
ECC requirements.

As far as I am aware, NAND manufacturers only guarantee that the
factory-programmed OOB BB markers are valid.  Nothing is mentioned in the
datasheets about using OOB BB markers to track worn blocks - they all tend to
recommend BBTs.

Cheers,

Angus