Index: head/sys/geom/mirror/g_mirror.h
===================================================================
--- head/sys/geom/mirror/g_mirror.h
+++ head/sys/geom/mirror/g_mirror.h
@@ -169,9 +169,11 @@
 #define	G_MIRROR_TYPE_AUTOMATIC	1
 
 /* Bump syncid on first write. */
-#define	G_MIRROR_BUMP_SYNCID	0x1
+#define	G_MIRROR_BUMP_SYNCID		0x1
 /* Bump genid immediately. */
-#define	G_MIRROR_BUMP_GENID	0x2
+#define	G_MIRROR_BUMP_GENID		0x2
+/* Bump syncid immediately. */
+#define	G_MIRROR_BUMP_SYNCID_NOW	0x4
 struct g_mirror_softc {
 	u_int		sc_type;	/* Device type (manual/automatic). */
 	u_int		sc_state;	/* Device state. */
Index: head/sys/geom/mirror/g_mirror.c
===================================================================
--- head/sys/geom/mirror/g_mirror.c
+++ head/sys/geom/mirror/g_mirror.c
@@ -982,7 +982,13 @@
 			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 &&
+				    bp->bio_cmd == BIO_READ)
+					sc->sc_bump_id |= G_MIRROR_BUMP_SYNCID;
+				else if (bp->bio_error == ENXIO)
+					sc->sc_bump_id |= G_MIRROR_BUMP_SYNCID_NOW;
+				else
+					sc->sc_bump_id |= G_MIRROR_BUMP_GENID;
 				g_mirror_event_send(disk,
 				    G_MIRROR_DISK_STATE_DISCONNECTED,
 				    G_MIRROR_EVENT_DONTWAIT);
@@ -2517,6 +2523,10 @@
 		if ((sc->sc_bump_id & G_MIRROR_BUMP_GENID) != 0) {
 			sc->sc_bump_id &= ~G_MIRROR_BUMP_GENID;
 			g_mirror_bump_genid(sc);
+		}
+		if ((sc->sc_bump_id & G_MIRROR_BUMP_SYNCID_NOW) != 0) {
+			sc->sc_bump_id &= ~G_MIRROR_BUMP_SYNCID_NOW;
+			g_mirror_bump_syncid(sc);
 		}
 		break;
 	default: