SMART said PASSED. The drive had 477 dead sectors.
We ran a drive-health campaign across thirteen boxes to find out whether early warning actually works. One drive was carrying 477 reallocated sectors and reported its own health as PASSED in all 140 readings we took, a full write-and-verify pass over it came back clean, and the four healthy drives we tried hardest to destroy refused to break. Including the part we cannot yet answer.