diff --git a/watcher/decision_engine/model/element/instance.py b/watcher/decision_engine/model/element/instance.py
index ebdb16d7b..c68841f76 100644
--- a/watcher/decision_engine/model/element/instance.py
+++ b/watcher/decision_engine/model/element/instance.py
@@ -42,6 +42,9 @@ class InstanceState(enum.Enum):
 class Instance(compute_resource.ComputeResource):
 
     fields = {
+        # If the resource is excluded by the scope,
+        # 'watcher_exclude' property will be set True.
+        "watcher_exclude": wfields.BooleanField(default=False),
         "state": wfields.StringField(default=InstanceState.ACTIVE.value),
 
         "memory": wfields.NonNegativeIntegerField(),
diff --git a/watcher/decision_engine/scope/compute.py b/watcher/decision_engine/scope/compute.py
index 41a4028e4..bfe0b729e 100644
--- a/watcher/decision_engine/scope/compute.py
+++ b/watcher/decision_engine/scope/compute.py
@@ -36,6 +36,12 @@ class ComputeScope(base.BaseScope):
         node = cluster_model.get_node_by_uuid(node_name)
         cluster_model.delete_instance(instance, node)
 
+    def update_exclude_instance(self, cluster_model, instance, node_name):
+        node = cluster_model.get_node_by_uuid(node_name)
+        cluster_model.unmap_instance(instance, node)
+        instance.update({"watcher_exclude": True})
+        cluster_model.map_instance(instance, node)
+
     def _check_wildcard(self, aggregate_list):
         if '*' in aggregate_list:
             if len(aggregate_list) == 1:
@@ -108,8 +114,9 @@ class ComputeScope(base.BaseScope):
                 self.remove_instance(cluster_model, instance, node_uuid)
             cluster_model.remove_node(node)
 
-    def remove_instances_from_model(self, instances_to_remove, cluster_model):
-        for instance_uuid in instances_to_remove:
+    def update_exclude_instance_in_model(
+            self, instances_to_exclude, cluster_model):
+        for instance_uuid in instances_to_exclude:
             try:
                 node_name = cluster_model.get_node_by_instance_uuid(
                     instance_uuid).uuid
@@ -119,7 +126,7 @@ class ComputeScope(base.BaseScope):
                             " instance was hosted on.",
                             instance_uuid)
                 continue
-            self.remove_instance(
+            self.update_exclude_instance(
                 cluster_model,
                 cluster_model.get_instance_by_uuid(instance_uuid),
                 node_name)
@@ -165,7 +172,7 @@ class ComputeScope(base.BaseScope):
                     nodes=nodes_to_exclude,
                     instance_metadata=instance_metadata)
 
-        instances_to_remove = set(instances_to_exclude)
+        instances_to_exclude = set(instances_to_exclude)
         if allowed_nodes:
             nodes_to_remove = set(model_hosts) - set(allowed_nodes)
         nodes_to_remove.update(nodes_to_exclude)
@@ -174,8 +181,9 @@ class ComputeScope(base.BaseScope):
 
         if instance_metadata and self.config.check_optimize_metadata:
             self.exclude_instances_with_given_metadata(
-                instance_metadata, cluster_model, instances_to_remove)
+                instance_metadata, cluster_model, instances_to_exclude)
 
-        self.remove_instances_from_model(instances_to_remove, cluster_model)
+        self.update_exclude_instance_in_model(instances_to_exclude,
+                                              cluster_model)
 
         return cluster_model
diff --git a/watcher/tests/decision_engine/scope/test_compute.py b/watcher/tests/decision_engine/scope/test_compute.py
index 33d22eaa9..f3b01556a 100644
--- a/watcher/tests/decision_engine/scope/test_compute.py
+++ b/watcher/tests/decision_engine/scope/test_compute.py
@@ -242,16 +242,22 @@ class TestComputeScope(base.TestCase):
             ('INSTANCE_7', 'Node_4')]
         self.assertEqual(sorted(expected_edges), sorted(model.edges()))
 
-    def test_remove_instances_from_model(self):
+    def test_update_exclude_instances_in_model(self):
         model = self.fake_cluster.generate_scenario_1()
         compute.ComputeScope([], mock.Mock(),
-                             osc=mock.Mock()).remove_instances_from_model(
+                             osc=mock.Mock()).update_exclude_instance_in_model(
             ['INSTANCE_1', 'INSTANCE_2'], model)
         expected_edges = [
             ('INSTANCE_0', 'Node_0'),
+            ('INSTANCE_1', 'Node_0'),
+            ('INSTANCE_2', 'Node_1'),
             ('INSTANCE_3', 'Node_2'),
             ('INSTANCE_4', 'Node_2'),
             ('INSTANCE_5', 'Node_2'),
             ('INSTANCE_6', 'Node_3'),
             ('INSTANCE_7', 'Node_4')]
         self.assertEqual(sorted(expected_edges), sorted(model.edges()))
+        self.assertFalse(
+            model.get_instance_by_uuid('INSTANCE_0').watcher_exclude)
+        self.assertTrue(
+            model.get_instance_by_uuid('INSTANCE_1').watcher_exclude)