Flash File Systems or Translation Layers?

marty fouts mf.danger at gmail.com
Thu May 18 02:25:27 UTC 2006


On 5/17/06, Benno Rice <benno at freebsd.org> wrote:
> gnn at freebsd.org wrote:
> > Howdy,
> >
> > So, a few of us have talked off list of the need for a flash file
> > system or translation layer for FreeBSD in order to better target the
> > kind of boards we want to support.  The one lead I had was to a poorly
> > written, binary only solution with nasty licensing.   That is, it was
> > a dead end.  Does anyone know of anything that exists now that we
> > might coopt or have the knowledge to do this right/well?
>
> I thought about doing a port of jffs2.  Probably a rewrite actually, so
> we can have a non-GPL version.  It's waiting on me getting to the point
> where I need it though. =)
>

You probably don't want jffs2, because it has, um, interesting,
performance characteristics. I also vaguely recall reading that the
authors had stopped development on jffs3.

Also, jffs requires MTD, and it's debatable whether a rewrite of MTD
would be a good thing or not.  See discussions on the yaffs mailing
list and, IIRC, one of the NetBSD mailing lists on this recently.

It's not clear to me that "flash" is a good dividing point for making
a file system. It seems a lot more likely that NOR and NAND flash are
enough different that they would require their own file systems, or,
at the least, their own address translation layers.

Marty


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