Re: data loss on jffs2 filesystem on dataflash

[Artem B. Bityutskiy]

Jörn Engel wrote:
> Still can't.  Block devices have the attribute that writing AAA... to
> a block containing BBB... gives you one of three possible results in
> case of power failure:
>
> 1. BBB...BBB all written
> 2. AAA...AAA nothing written
> 3. AAA...BBB partially written.
>
> Flash doesn't have 3, but two more cases:
> 4. FFF...FFF erased, nothing written
> 5. AAA...FFF erased, partially written
>
> Plus the really obnoxious
> 6. FFF...FFF partially erased.  Looks fine but some bits may flip
>    randomly, writes may not stick, etc.
>
> Now try finding a filesystem that is robust if 4-6 happens. ;)
Don't underastand this. If you mean the atomicity, CRC may help here. 
And no problems. Or may be you missed the the fact that we have 
eraseblock size = writeblock size?

> > JFFS2 orients to "classical" flashes. They have no "write page with 
> > built-in erase" operation.
> What does this thing do?
It erases individual page, then writes there. To put it differently, in 
your terminology, eraseblock size = writeblock size.

P.S. I actually missed the mailing list, this should have gone to the 
MTD ML. So let's move there please.

--
Best Regards,
Artem B. Bityuckiy,
St.-Petersburg, Russia.

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