Enhanced stc-warden monitor tool to check disk being write-able.

Change-Id: Ic684025cf463a8f5864355a3a26bbda7b166af32
diff --git a/tools/test/bin/stc-warden b/tools/test/bin/stc-warden
index 20baff2..24a924a 100755
--- a/tools/test/bin/stc-warden
+++ b/tools/test/bin/stc-warden
@@ -11,6 +11,10 @@
 for slave in $CELL_SLAVES; do
     echo "========================================================"
     echo "$slave:"
+    ssh sdn@$slave "touch foo && echo 'Disk OK' || echo 'Disk READ-ONLY'"
+    let ok=ok+$?
+    ssh sdn@$slave "df -h /"
+    let ok=ok+$?
     ssh sdn@$slave sudo lxc-ls --fancy
     let ok=ok+$?
 done