This counter indicates the number of times this physical drive returned a bad hardware status, noting that the drive may ultimately be failed if retries do not resolve the condition, with 4,294,967,295 returned if the value cannot be determined. An admin watches this as an early signal that a drive's hardware is misbehaving, potentially before the drive is formally marked as failed. For example, a rising hardware error count on a drive still reporting ok status would justify scheduling a proactive replacement.