diff --git a/sys/cam/scsi/scsi_da.c b/sys/cam/scsi/scsi_da.c
--- a/sys/cam/scsi/scsi_da.c
+++ b/sys/cam/scsi/scsi_da.c
@@ -2198,7 +2198,8 @@
 		ccb = (union ccb *)arg;
 
 		/*
-		 * Handle all UNIT ATTENTIONs except our own, as they will be
+		 * Unit attentions are broadcast to all the LUNs of the device
+		 * so handle all UNIT ATTENTIONs except our own, as they will be
 		 * handled by daerror().
 		 */
 		if (xpt_path_periph(ccb->ccb_h.path) != periph &&
@@ -6028,6 +6029,16 @@
 			/* 28/0: NOT READY TO READY CHANGE, MEDIUM MAY HAVE CHANGED */
 			softc->flags &= ~DA_FLAG_PROBED;
 			disk_media_changed(softc->disk, M_NOWAIT);
+			/*
+			 * In an ideal world, we'd make sure that we have the
+			 * same medium mounted (if we'd seen one already) but
+			 * instead we don't invalidate the pack here and flag
+			 * below to retry the UAs. If we exhaust retries, then
+			 * we'll invalidate it in dadone for ENXIO errors (which
+			 * 28/0 will fail with eventually). Usually, retrying
+			 * just works and/or we get this before we've opened the
+			 * device (which clears the invalid flag).
+			 */
 		} else if (sense_key == SSD_KEY_UNIT_ATTENTION &&
 		    asc == 0x3F && ascq == 0x03) {
 			/* 3f/3: INQUIRY DATA HAS CHANGED */