Index: sys/geom/mirror/g_mirror.c
===================================================================
--- sys/geom/mirror/g_mirror.c
+++ sys/geom/mirror/g_mirror.c
@@ -982,7 +982,10 @@
 			if (g_mirror_disconnect_on_failure &&
 			    g_mirror_ndisks(sc, G_MIRROR_DISK_STATE_ACTIVE) > 1)
 			{
-				sc->sc_bump_id |= G_MIRROR_BUMP_GENID;
+				if (bp->bio_error == ENXIO)
+					sc->sc_bump_id |= G_MIRROR_BUMP_SYNCID;
+				else
+					sc->sc_bump_id |= G_MIRROR_BUMP_GENID;
 				g_mirror_event_send(disk,
 				    G_MIRROR_DISK_STATE_DISCONNECTED,
 				    G_MIRROR_EVENT_DONTWAIT);