diff --git a/nova/compute/api.py b/nova/compute/api.py
index afd800ce3ead..e49658495db4 100644
--- a/nova/compute/api.py
+++ b/nova/compute/api.py
@@ -3299,11 +3299,11 @@ class AggregateAPI(base.Base):
         aggregate = objects.Aggregate.get_by_id(context, aggregate_id)
         if 'name' in values:
             aggregate.name = values.pop('name')
+            aggregate.save()
         self.is_safe_to_update_az(context, values, aggregate=aggregate,
                                   action_name="update_aggregate")
         if values:
-            aggregate.metadata = values
-        aggregate.save()
+            aggregate.update_metadata(values)
         # If updated values include availability_zones, then the cache
         # which stored availability_zones and host need to be reset
         if values.get('availability_zone'):
diff --git a/nova/tests/compute/test_compute.py b/nova/tests/compute/test_compute.py
index 6ee4fd50015d..35af1210ed08 100644
--- a/nova/tests/compute/test_compute.py
+++ b/nova/tests/compute/test_compute.py
@@ -9430,10 +9430,10 @@ class ComputeAPIAggrTestCase(BaseTestCase):
         self.assertEqual(len(fake_notifier.NOTIFICATIONS), 2)
         msg = fake_notifier.NOTIFICATIONS[0]
         self.assertEqual(msg.event_type,
-                         'aggregate.updateprop.start')
+                         'aggregate.updatemetadata.start')
         msg = fake_notifier.NOTIFICATIONS[1]
         self.assertEqual(msg.event_type,
-                         'aggregate.updateprop.end')
+                         'aggregate.updatemetadata.end')
 
     def test_update_aggregate_az_fails(self):
         # Ensure aggregate's availability zone can't be updated,
@@ -9459,10 +9459,10 @@ class ComputeAPIAggrTestCase(BaseTestCase):
         self.assertEqual(len(fake_notifier.NOTIFICATIONS), 15)
         msg = fake_notifier.NOTIFICATIONS[13]
         self.assertEqual(msg.event_type,
-                         'aggregate.updateprop.start')
+                         'aggregate.updatemetadata.start')
         msg = fake_notifier.NOTIFICATIONS[14]
         self.assertEqual(msg.event_type,
-                         'aggregate.updateprop.end')
+                         'aggregate.updatemetadata.end')
 
     def test_update_aggregate_az_fails_with_nova_az(self):
         # Ensure aggregate's availability zone can't be updated,
@@ -9566,6 +9566,22 @@ class ComputeAPIAggrTestCase(BaseTestCase):
         self.assertEqual(msg.event_type,
                          'aggregate.updatemetadata.end')
 
+    def test_update_aggregate_az_do_not_replace_existing_metadata(self):
+        # Ensure that that update of the aggregate availability zone
+        # does not replace the aggregate existing metadata
+        aggr = self.api.create_aggregate(self.context, 'fake_aggregate',
+                                         'fake_zone')
+        metadata = {'foo_key1': 'foo_value1'}
+        aggr = self.api.update_aggregate_metadata(self.context,
+                                                  aggr['id'],
+                                                  metadata)
+        metadata = {'availability_zone': 'new_fake_zone'}
+        aggr = self.api.update_aggregate(self.context,
+                                         aggr['id'],
+                                         metadata)
+        self.assertThat(aggr['metadata'], matchers.DictMatches(
+            {'availability_zone': 'new_fake_zone', 'foo_key1': 'foo_value1'}))
+
     def test_update_aggregate_metadata_az_fails(self):
         # Ensure aggregate's availability zone can't be updated,
         # when aggregate has hosts in other availability zone