Trying to find datasheets of the flash chips to know what their erase block size and page size(and number of erase cycles) has been a nightmare for me, the manufacturer just doesn't care if your partitioning choice ends up sending the SSD/SD/MMC sooner than the warranty expires. Have you had the same experience?
Best regards On Mon, Oct 5, 2009 at 11:07 PM, Mitch Bradley <w...@laptop.org> wrote: > David might be right in principle, but when component price matters, you > have to buy the hardware that the mass market offers. Right now the > sweet spot is "smart" devices with embedded Flash Translation Layer > firmware. I'd place my bet on that trend continuing. > > Linux does not "drive" the mass market. Asian volume manufacturers > barely know what Linux is. Maybe that is changing, but there is a long > way to go before the reality on the ground changes. > > David minimizes the impact of NAND geometry changes. The reality is > that it doesn't have to change "that much" to "flip" the decision. We > at OLPC tried in vain to find a way to get past 2 GiB with the internal > NAND. The problem is that the controller hardware is coupled to the > NAND technology (MLC vs SLC) and page size. The coupling is caused by > the fact that the error correcting codes must be tuned to those > factors. ECC for 2K-page SLC is just no good for 4K MLC. ECC > generation and checking must be done in hardware for adequate > performance. Our existing NAND controller just didn't work for the > generation of chips that has largely supplanted the chips we were using. > > So get a new controller, right? Well, if you go and try to buy one, you > will find that they all come with embedded microprocessors that > implement a Flash Translation Layer, and the manufacturers closely guard > the operational details. It would be nice if they would reveal their > secrets so the FOSS community could write some "better" firmware for > those controllers. Good luck making that happen. And good luck getting > it deployed before the chip has been superseded. > > You might think that System on Chip devices for the embedded market > might yield a different answer. That's not what we saw. Every time we > looked at an SoC presentation, invariably the device did not have a > suitable raw NAND controller. That is what started me to thinking that > raw NAND was about to get killed in the market by "managed NAND". > Everything these days has an SD controller or three. > > David is absolutely right that many of the current FTL-equipped devices > are nearly hopeless. But that is not the same as saying that they all > are. A few devices have done quite well in our stress testing. Over > time, I expect the situation to get better and better as the firmware > that "gets it right" supplants the earlier tries. > > _______________________________________________ > Devel mailing list > Devel@lists.laptop.org > http://lists.laptop.org/listinfo/devel > _______________________________________________ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
