(This question is also relevant to certain robots on Mars.) I bought a number of questionable flash memory cards (formatted as FAT32), and I wasn't disappointed with their questionableness -- they're failing, so I've been trying to figure out their failure modes w/o having access to their internal management software. They are showing bizarre failure modes. The files don't seem to be failing in a single block, but the failures seem to be more global. For example, a folder will cease being a folder, and look like a regular file, while the files in the folder can be recovered by file checking software. I see almost no failures (= modifications) on files less than 100Mbytes, but nearly 100% failures on files >200Mbytes. Has anyone else here studied flash memory card (uSD card) failures? Is there any software on the internet that can pinpoint failures so that I can simply remove these blocks from consideration? (I realize that it's cheaper to buy new uSD cards, but I thought it would be fun to understand the failures.)