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Thanks for the extra references! I'll make sure to bookmark those and take a closer look later. Yeah, MLC already losing data after 3 months doesn't really sur

Thanks for the extra references! I'll make sure to bookmark those and take a closer look later. Yeah, MLC already losing data after 3 months doesn't really surprise me that much. If you play with a raw MLC chip and turn off the ECC engine, the amount of bit flips you get from reading on some chips isn't even funny anymore. With one chip I tried, even with ECC, I managed to induce persistent bit flips fairly quickly just by reading the same physical page over-and-over. For extra fun: those bit flips can happen in another page that you didn't touch, because the bits are paired :-) What actually still does surprise me sometimes, is how reliable those things can work after all, if you just pile enough software abstraction and management on top.

dale_glass 2y ago
You seem like the sort of person who'd know. Are there tools available to a normal person to take a look at this stuff? Eg, is there some way I can evaluate a not yet failing SD card? CDs had tools to check for C1 and C2 errors, is there a way to do the same with a SD card or SSD?
- st_goliath 2y ago
  For SSD, I'd imagine you might get SMART data or something similar? I know that on Linux, there are mmc-utils, but I only used those with eMMC so far. I just tried to read out some general status information on uSD cards I have around: it didn't work for 2 Kingston and Acon cards (command timeout). But for a Swissbit card (industrial), it took some solid 10 seconds before reporting back that it's doing ok and is ready for data. Looks like it depends heavily on vendor support, possibly also undocumented/non-standard command sequences?