diff --git a/nova/scheduler/host_manager.py b/nova/scheduler/host_manager.py
index 009767b04993..6a8b7fc0b9fd 100644
--- a/nova/scheduler/host_manager.py
+++ b/nova/scheduler/host_manager.py
@@ -427,7 +427,7 @@ class HostManager(object):
             count = 0
             if not computes_by_cell:
                 computes_by_cell = {}
-                for cell in self.cells:
+                for cell in self.cells.values():
                     with context_module.target_cell(context, cell) as cctxt:
                         cell_cns = objects.ComputeNodeList.get_all(
                             cctxt).objects
@@ -654,24 +654,26 @@ class HostManager(object):
                 temp_cells.objects.remove(c)
                 # once its done break for optimization
                 break
-        # NOTE(danms, tssurya): global list of cells cached which
-        # will be refreshed every time a SIGHUP is sent to the scheduler.
-        self.cells = temp_cells
+        # NOTE(danms, tssurya): global dict, keyed by cell uuid, of cells
+        # cached which will be refreshed every time a SIGHUP is sent to the
+        # scheduler.
+        self.cells = {cell.uuid: cell for cell in temp_cells}
         LOG.debug('Found %(count)i cells: %(cells)s',
                   {'count': len(self.cells),
-                   'cells': ', '.join([c.uuid for c in self.cells])})
+                   'cells': ', '.join(self.cells)})
         # NOTE(tssurya): Global cache of only the enabled cells. This way
         # scheduling is limited only to the enabled cells. However this
         # cache will be refreshed every time a cell is disabled or enabled
         # or when a new cell is created as long as a SIGHUP signal is sent
         # to the scheduler.
-        self.enabled_cells = [c for c in self.cells if not c.disabled]
+        self.enabled_cells = [c for c in temp_cells if not c.disabled]
         # Filtering the disabled cells only for logging purposes.
-        disabled_cells = [c for c in self.cells if c.disabled]
-        LOG.debug('Found %(count)i disabled cells: %(cells)s',
-                  {'count': len(disabled_cells),
-                   'cells': ', '.join(
-                   [c.identity for c in disabled_cells])})
+        if LOG.isEnabledFor(logging.DEBUG):
+            disabled_cells = [c for c in temp_cells if c.disabled]
+            LOG.debug('Found %(count)i disabled cells: %(cells)s',
+                      {'count': len(disabled_cells),
+                       'cells': ', '.join(
+                       [c.identity for c in disabled_cells])})
 
     def get_host_states_by_uuids(self, context, compute_uuids, spec_obj):
 
diff --git a/nova/tests/unit/scheduler/test_host_manager.py b/nova/tests/unit/scheduler/test_host_manager.py
index c6997ec95622..faad28d59eda 100644
--- a/nova/tests/unit/scheduler/test_host_manager.py
+++ b/nova/tests/unit/scheduler/test_host_manager.py
@@ -108,10 +108,12 @@ class HostManagerTestCase(test.NoDBTestCase):
                         return_value=cells) as mock_cm:
             self.host_manager.refresh_cells_caches()
             mock_cm.assert_called_once()
+        # Cell2 is not in the enabled list.
         self.assertEqual(2, len(self.host_manager.enabled_cells))
         self.assertEqual(cell_uuid3, self.host_manager.enabled_cells[1].uuid)
+        # But it is still in the full list.
         self.assertEqual(3, len(self.host_manager.cells))
-        self.assertEqual(cell_uuid2, self.host_manager.cells[1].uuid)
+        self.assertIn(cell_uuid2, self.host_manager.cells)
 
     def test_refresh_cells_caches_except_cell0(self):
         ctxt = nova_context.RequestContext('fake-user', 'fake_project')
@@ -546,7 +548,7 @@ class HostManagerTestCase(test.NoDBTestCase):
         mock_get_by_binary.return_value = fakes.SERVICES
         context = 'fake_context'
         compute_nodes, services = self.host_manager._get_computes_for_cells(
-            context, self.host_manager.cells)
+            context, self.host_manager.enabled_cells)
 
         # _get_host_states returns a generator, so make a map from it
         host_states_map = {(state.host, state.nodename): state for state in
@@ -612,7 +614,7 @@ class HostManagerTestCase(test.NoDBTestCase):
 
         context = nova_context.get_admin_context()
         compute_nodes, services = self.host_manager._get_computes_for_cells(
-            context, self.host_manager.cells)
+            context, self.host_manager.enabled_cells)
 
         hosts = self.host_manager._get_host_states(
             context, compute_nodes, services)
@@ -641,7 +643,7 @@ class HostManagerTestCase(test.NoDBTestCase):
 
         context = nova_context.get_admin_context()
         compute_nodes, services = self.host_manager._get_computes_for_cells(
-            context, self.host_manager.cells)
+            context, self.host_manager.enabled_cells)
 
         hosts = self.host_manager._get_host_states(
             context, compute_nodes, services)
@@ -672,7 +674,7 @@ class HostManagerTestCase(test.NoDBTestCase):
 
         context = nova_context.get_admin_context()
         compute_nodes, services = self.host_manager._get_computes_for_cells(
-            context, self.host_manager.cells)
+            context, self.host_manager.enabled_cells)
 
         hosts = self.host_manager._get_host_states(
             context, compute_nodes, services)
@@ -718,7 +720,7 @@ class HostManagerTestCase(test.NoDBTestCase):
 
         context = nova_context.get_admin_context()
         compute_nodes, services = self.host_manager._get_computes_for_cells(
-            context, self.host_manager.cells)
+            context, self.host_manager.enabled_cells)
 
         self.host_manager._get_host_states(context, compute_nodes, services)
 
@@ -1077,7 +1079,7 @@ class HostManagerChangedNodesTestCase(test.NoDBTestCase):
         context = 'fake_context'
 
         compute_nodes, services = self.host_manager._get_computes_for_cells(
-            context, self.host_manager.cells)
+            context, self.host_manager.enabled_cells)
 
         # _get_host_states returns a generator, so make a map from it
         host_states_map = {(state.host, state.nodename): state for state in
@@ -1103,7 +1105,7 @@ class HostManagerChangedNodesTestCase(test.NoDBTestCase):
 
         # first call: all nodes
         compute_nodes, services = self.host_manager._get_computes_for_cells(
-            context, self.host_manager.cells)
+            context, self.host_manager.enabled_cells)
         hosts = self.host_manager._get_host_states(
             context, compute_nodes, services)
         # _get_host_states returns a generator, so make a map from it
@@ -1113,7 +1115,7 @@ class HostManagerChangedNodesTestCase(test.NoDBTestCase):
 
         # second call: just running nodes
         compute_nodes, services = self.host_manager._get_computes_for_cells(
-            context, self.host_manager.cells)
+            context, self.host_manager.enabled_cells)
         hosts = self.host_manager._get_host_states(
             context, compute_nodes, services)
         host_states_map = {(state.host, state.nodename): state for state in
@@ -1133,7 +1135,7 @@ class HostManagerChangedNodesTestCase(test.NoDBTestCase):
 
         # first call: all nodes
         compute_nodes, services = self.host_manager._get_computes_for_cells(
-            context, self.host_manager.cells)
+            context, self.host_manager.enabled_cells)
         hosts = self.host_manager._get_host_states(
             context, compute_nodes, services)
         # _get_host_states returns a generator, so make a map from it
@@ -1143,7 +1145,7 @@ class HostManagerChangedNodesTestCase(test.NoDBTestCase):
 
         # second call: no nodes
         compute_nodes, services = self.host_manager._get_computes_for_cells(
-            context, self.host_manager.cells)
+            context, self.host_manager.enabled_cells)
         hosts = self.host_manager._get_host_states(
             context, compute_nodes, services)
         host_states_map = {(state.host, state.nodename): state for state in