> I thought the whole point of running the SMART tests was to detect > a failing disk, so color me confused.
If we knew how to detect a failing (as opposed to failed) disk, then things would be easy. SMART is an attempt to provide relevant information, but that's all. AFAIK, it's still "the best we have", but it's not a reliable way to answer the question (I'm not even sure the question is well-defined, to be honest). Stefan