diff --git a/nova/compute/cells_api.py b/nova/compute/cells_api.py
index c7cbc76f2f98..b147c282b13a 100644
--- a/nova/compute/cells_api.py
+++ b/nova/compute/cells_api.py
@@ -199,6 +199,13 @@ class ComputeCellsAPI(compute_api.API):
         """
         return super(ComputeCellsAPI, self).create(*args, **kwargs)
 
+    def _update_block_device_mapping(self, *args, **kwargs):
+        """Don't create block device mappings in the API cell.
+
+        The child cell will create it and propagate it up to the parent cell.
+        """
+        pass
+
     def update(self, context, instance, **kwargs):
         """Update an instance."""
         cell_name = instance['cell_name']
diff --git a/nova/tests/unit/compute/test_compute_cells.py b/nova/tests/unit/compute/test_compute_cells.py
index 4669f9871d82..15da4e8bfb50 100644
--- a/nova/tests/unit/compute/test_compute_cells.py
+++ b/nova/tests/unit/compute/test_compute_cells.py
@@ -22,6 +22,7 @@ import mock
 from oslo.config import cfg
 from oslo.utils import timeutils
 
+from nova import block_device
 from nova.cells import manager
 from nova.compute import api as compute_api
 from nova.compute import cells_api as compute_cells_api
@@ -180,6 +181,19 @@ class CellsComputeAPITestCase(test_compute.ComputeAPITestCase):
 
         self.assertEqual(migrations, response)
 
+    def test_update_block_device_mapping(self):
+        instance_type = {'swap': 1, 'ephemeral_gb': 1}
+        instance = self._create_fake_instance_obj()
+        bdms = [block_device.BlockDeviceDict({'source_type': 'image',
+                                              'destination_type': 'local',
+                                              'image_id': 'fake-image',
+                                              'boot_index': 0})]
+        self.compute_api._update_block_device_mapping(
+            instance_type, instance.uuid, bdms)
+        bdms = db.block_device_mapping_get_all_by_instance(
+            self.context, instance['uuid'])
+        self.assertEqual(0, len(bdms))
+
     @mock.patch('nova.cells.messaging._TargetedMessage')
     def test_rebuild_sig(self, mock_msg):
         # TODO(belliott) Cells could benefit from better testing to ensure API