JFFS2: checking CRCs twice!?

[Josh Boyer]

On Wed, 2005-01-12 at 12:26, Jörn Engel wrote:
> On Wed, 12 January 2005 15:11:09 +0000, Artem B. Bityuckiy wrote:
> > On Wed, 12 Jan 2005, Steven Scholz wrote:
> > 
> > > If a sector got broken just by reading it then the whole embedded system is 
> > > broken and has to be replaced ...
> 
> Amen, brother!
> 
> > This seems to be true for NOR. But  chrcking CRC helps at least *detect* 
> > and *report* media problems.
> 
> Well, more and more I come to the conclusion that media problems are a
> non-issue.  At least, flashes are about as reliable as hard drives.

I've seen them fail.  Multiple times.  And yes, the CRCs detected it and
helped me figure out that the hardware was borked.

You may be right that failures are rare, and when they do occur the
flash definitely needs to be replaced.  But I'd much rather debug a card
that had CRC errors than one that just had apps mysteriously getting
SIGILL because a bit flipped and the filesystem didn't bother to verify
the data before using it.

Unless you'd be willing to debug all those cards for me.  In that case,
I'm all for whatever you decide to do with CRCs :).  Until then, I'd
prefer that they stay.

josh