On Fri, 2023-04-14 at 17:34 -0400, Genes Lists wrote: > And no, its not 'stale' data, blocks that have not changed are fetched > from buffer cache. Hi, the kernel only knows access via software, it cannot know when something will break in the hardware without any feedback. If a nano thing in an external memory chip connected by USB breaks, e.g. on an SD card, external SSD etc., the cached block in the main memory cache of the computer is still ok. A mechanism that is superb for performance could be a problem when trying to check integrity of copied files. It's even possible that the data is ok, when reading it from an external memory chip, but directly after reading it, it is corrupted by an hardware issue, but it's still more reliable than checking against cached data, provided by the internal main memory. Regards, Ralf
