diff --git a/daemon/pnfs.h b/daemon/pnfs.h
index 748d498..e79df25 100644
--- a/daemon/pnfs.h
+++ b/daemon/pnfs.h
@@ -42,7 +42,11 @@
 # endif
 
 # define PNFS_THREADING
-# define PNFS_THREAD_BY_SERVER
+
+/* XXX: the thread-by-server model breaks down when using dense layouts,
+ * because multiple stripes could be mapped to a single data server, and
+ * the per-data-server thread would have to send a COMMIT for each stripe */
+//# define PNFS_THREAD_BY_SERVER
 
 #endif