Re: nand flash

["Toru Nishimura" <locore64%alkyltechnology.com@localhost>]

Yocto points me;

> Could LFS be more appropriate for 'wear levelling' ?
> Especially now that we can use it as root filesystem...

That's the long-standing argument to be proven by field practices.

The peculiarity of NAND erase constraint brings the consequence
that the best NAND write policy is to allocate fresh blocks all the time.
Never write-back to the existing blocks when they get modified.
This is a very comfortable match with the approarch behind BSDLFS.

Please remind the write-locality issue, excessive write in limited
portions of the whole store, is to happen at meta data updates,
like to grow directory or to maintain super block(s).

It was interesting experience to see the spacial write locality recorded
by write counter values of 4C81 NAND, with variety of faked disklabel
"geometries" and FFS build parameters.  I guess such the research
has never been done so far.  Good for under-grad student home work...

Toru Nishimura/ALKYL Technology