Re: [RFC] read-only filesystem support for NAND flash devices

Josh Boyer
2006-05-10T20:11:42Z

On 5/10/06, Jörn Engel <joern@wohnheim.fh-wedel.de> wrote:
> On Wed, 10 May 2006 15:20:44 +0400, Vitaly Wool wrote:
> > Josh Boyer wrote:
> >
> > >Not quite the case. You need bad block skipping, yes. But NAND can
> > >get bit flips in good blocks still. How do you deal with that? You
> > >can't leave the block in that state forever because it will continue
> > >to get bit flips and then your data will be unusable.
> > Yep, I know about the issue. The recommended way to go here AFAIK is to
> > mark the block as bad and copy its contents to a free one.
> > However, this will make mapping a lot more complicated so I'd like to go
> > another way, i. e. erasing and rewriting this very block, and if it
> > wears out, cache the data read from it and schedule moving the data
> > forward within the partition in a background. Does that make sense?
>
> Or you could just ignore the issue. The way I read it, your RFC is
> basically "Don't do the real thing, just a quick hack to make it work
> at all." Which is perfectly fine to me. It is not perfect, but that
> is well documented and if people actually use it and care a lot about
> some particular deficiency, you can solve it then.

That's a perfectly acceptable approach to me. I was just pointing
something out in case someone already cared enough about it to solve
it now.

josh