Hi Ulf, Arnd, do you guys have any thoughts on this? Kind regards, Johan 2014-09-03 16:24 GMT+02:00 Johan Rudholm <jrudholm@xxxxxxxxx>: > Hi all, > > as you know, NAND flash can be programmed a limited number of times > before it reaches end of life, the number of times varies with the > NAND technology used, among other things. > > As far as I can tell from the simplified SD-spec, there is no way of > asking the card about how many program/erase cycles it can handle, or > how many p/e cycles are left before reaching EOL. Right? > > So, if one should want to give the user some kind of early warning > that it's time to change SD-cards, is there a way? Also, when a card > has reached EOL, is there a way of telling this condition apart from > all other error conditions that may arise? As you know, depending on > the quality of the card and controller, read timeouts, write timeouts, > lockups etc may occur but can usually be fixed with a power cycle. > > I'm thinking of collecting simple statistics from for instance > card/block.c and exposing it via an ioctl or sysfs. The statistics can > be gathered and processed by some user space process which can > determine if the user needs to be alerted. The statistics can be, for > instance: > > * Writes/reads that timeout, but succeed after a retry > * Writes/reads that timeout and never succeeds > * Different kinds of errors in the card status > * Anything else? > > Perhaps it's not possible to detect worn out cards this way, but at > least it could point out and warn about crappy cards? > > Any thoughts about this? > > Kind regards, Johan -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
