diff --git a/sys/cam/cam_periph.c b/sys/cam/cam_periph.c
--- a/sys/cam/cam_periph.c
+++ b/sys/cam/cam_periph.c
@@ -1888,13 +1888,31 @@
 
 	/* Filter the errors that should be reported via devctl */
 	switch (ccb->ccb_h.status & CAM_STATUS_MASK) {
+	case CAM_SCSI_STATUS_ERROR: {
+		int serr, sk, asc, ascq;
+
+		if (scsi_extract_sense_ccb(ccb, &serr, &sk, &asc, &ascq) &&
+		    sk == SSD_KEY_ILLEGAL_REQUEST) {
+			/*
+			 * Don't log illegal requests. These are often used to
+			 * probe what a drive can do, often by programs like
+			 * smartctl that lose this knowledge from run to run.
+			 * It doesn't seem useful to assess the health or other
+			 * characteristics of a specific drive. We can't spike
+			 * the error (the caller needs to see it), so we have
+			 * to do this off filtering here.
+			 */
+			break;
+		}
+		devctl_err++;
+		break;
+	}
 	case CAM_CMD_TIMEOUT:
 	case CAM_REQ_ABORTED:
 	case CAM_REQ_CMP_ERR:
 	case CAM_REQ_TERMIO:
 	case CAM_UNREC_HBA_ERROR:
 	case CAM_DATA_RUN_ERR:
-	case CAM_SCSI_STATUS_ERROR:
 	case CAM_ATA_STATUS_ERROR:
 	case CAM_SMP_STATUS_ERROR:
 	case CAM_DEV_NOT_THERE: