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Message-ID: <e2e108260805070058p476901f5ta4c38e99e1421eec@mail.gmail.com>
Date: Wed, 7 May 2008 09:58:56 +0200
From: "Bart Van Assche" <bart.vanassche@gmail.com>
To: "Tomasz Chmielewski" <mangoo@wpkg.org>
Subject: Re: Compact Flash Question
Cc: LKML <linux-kernel@vger.kernel.org>, YSadgat1@gcte.com,
       linux-os@analogic.com, Alan <alan@lxorguk.ukuu.org.uk>,
       "Linux IDE" <linux-ide@vger.kernel.org>
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On Wed, May 7, 2008 at 9:54 AM, Tomasz Chmielewski <mangoo@wpkg.org> wrote:
> How does it work, then?
> How can it do wear levelling over the whole CF if some (or most) area of CF
> is already used by our precious data/metadata?
> It would have to know the areas where no data is stored, but it contradicts
> the CF <-> filesystem separation.

The wear leveling algorithm even works if the CompactFlash controller
has no knowledge of the sectors on which filesystem data is stored.
All that is needed is some spare space on the CompactFlash that is not
made visible through the IDE interface, a controller that is able to
remap sectors and that stores this mapping persistently.

Bart.