On Wed, 4 Feb 2009, Mitch Bradley wrote: > Benjamin M. Schwartz wrote: >> -----BEGIN PGP SIGNED MESSAGE----- >> Hash: SHA1 >> >> Mitch Bradley wrote: >> >>> It has been my experience that USB sticks and SD cards with intact >>> factory formatting tend to last longer and run faster than ones that >>> have been reformatted with random layouts. >>> >> >> This gives us Linux users a bit of a dilemma if we want to use FTL flash >> for primary storage. FAT does not provide the file access permissions, >> symlinks, hardlinks, or even case sensitivity, that we desire for most >> filesystems on unixy systems. However, FTL devices behave as a sort of >> FAT-oriented black box, full of secret proprietary firmware that loves >> FAT. > > I think that FTLs are getting better over time, so maybe the > FAT-specific optimizations are starting to be replaced by more generic > algorithms. The rapidly growing market for FLASH-based storage is > certainly attracting lots of development dollars. > > In the absence of FAT-specific optimizations, perhaps properly-aligned > ext2 layouts will work well. > > Another solution is to choose high-quality devices. I've had good > results with some models from SanDisk and Transcend. But sometimes it > comes at a cost penalty - the really good SanDisk "Extreme III" SD cards > cost 2.5x the going rate for commodity cards of the same capacity. The > good cards appear to be rather more tolerant of "abuse" than the El > Cheapo's. But even with the tough ones, I think its prudent to treat > them gently.
the small devices are cheap enough, I'll bet a lot of people would be willing to chip in a few bucks if someone were to orginize a controlled test (or possibly one of the hardware websites can be prodded into doing a long enough and large enough test to have some valid statistics) >> One obvious proposal, therefore, would be to use FAT for storage, >> but wrap it with a layer that implements all our favorite POSIX stuff. >> the problem with this is that your access won't follow the FAT pattern anymore, it will follow the pattern of the higher-level filesystem. also, most setups like this that I have seen concentrate the 'extra' metadata for read efficiancy, but that's exactly the wrong thing to do for flash. David Lang _______________________________________________ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel