Index: geom_vinum.c
===================================================================
--- geom_vinum.c	(revision 202974)
+++ geom_vinum.c	(revision 204886)
@@ -788,7 +788,15 @@
 					    "completely accessible", p->name);
 					break;
 				}
+				if (p->flags & GV_PLEX_SYNCING ||
+				    p->flags & GV_PLEX_REBUILDING ||
+				    p->flags & GV_PLEX_GROWING) {
+					G_VINUM_DEBUG(0, "plex %s is busy with "
+					    "syncing or parity build", p->name);
+					break;
+				}
 				p->synced = 0;
+				p->flags |= GV_PLEX_REBUILDING;
 				g_topology_assert_not();
 				g_topology_lock();
 				err = gv_access(p->vol_sc->provider, 1, 1, 0);
@@ -811,6 +819,13 @@
 					    "completely accessible", p->name);
 					break;
 				}
+				if (p->flags & GV_PLEX_SYNCING ||
+				    p->flags & GV_PLEX_REBUILDING ||
+				    p->flags & GV_PLEX_GROWING) {
+					G_VINUM_DEBUG(0, "plex %s is busy with "
+					    "syncing or parity build", p->name);
+					break;
+				}
 				p->synced = 0;
 				g_topology_assert_not();
 				g_topology_lock();