// END realtime metrics:
	scannerMetricLastRealtime

	// Trace only metrics:
	scannerMetricScanFolder      // Scan a folder on disk, recursively.
	scannerMetricScanCycle       // Full cycle, cluster global
	scannerMetricScanBucketDrive // Single bucket on one drive
	scannerMetricCompactFolder   // Folder compacted.

	// Must be last:
	scannerMetricLast
)

// log scanner action.
// Use for s > scannerMetricStartTrace