gistfile1.txt

diff --git a/nova/scheduler/simple.py b/nova/scheduler/simple.py
index fc1b314..b6cbff4 100644
--- a/nova/scheduler/simple.py
+++ b/nova/scheduler/simple.py
@@ -42,10 +42,13 @@ class SimpleScheduler(chance.ChanceScheduler):
     def _schedule_instance(self, context, instance_id, *_args, **_kwargs):
         """Picks a host that is up and has the fewest running instances."""
         instance_ref = db.instance_get(context, instance_id)
-        if (instance_ref['availability_zone']
-            and ':' in instance_ref['availability_zone']
-            and context.is_admin):
-            zone, _x, host = instance_ref['availability_zone'].partition(':')
+
+        availability_zone = instance_ref.get('availability_zone')
+        zone, host = None, None
+        if availability_zone:
+            zone, _x, host = availability_zone.partition(':')
+
+        if host and context.is_admin:
             service = db.service_get_by_args(context.elevated(), host,
                                              'nova-compute')
             if not self.service_is_up(service):
@@ -57,7 +60,11 @@ class SimpleScheduler(chance.ChanceScheduler):
             db.instance_update(context, instance_id, {'host': host,
                                                       'scheduled_at': now})
             return host
+
         results = db.service_get_all_compute_sorted(context)
+        if zone:
+            results = [(service, cores) for (service, cores) in results
+                       if service['availability_zone'] == zone]
         for result in results:
             (service, instance_cores) = result
             if instance_cores + instance_ref['vcpus'] > FLAGS.max_cores:
@@ -84,10 +91,13 @@ class SimpleScheduler(chance.ChanceScheduler):
     def schedule_create_volume(self, context, volume_id, *_args, **_kwargs):
         """Picks a host that is up and has the fewest volumes."""
         volume_ref = db.volume_get(context, volume_id)
-        if (volume_ref['availability_zone']
-            and ':' in volume_ref['availability_zone']
-            and context.is_admin):
-            zone, _x, host = volume_ref['availability_zone'].partition(':')
+
+        availability_zone = volume_ref.get('availability_zone')
+        zone, host = None, None
+        if availability_zone:
+            zone, _x, host = availability_zone.partition(':')
+
+        if host and context.is_admin:
             service = db.service_get_by_args(context.elevated(), host,
                                              'nova-volume')
             if not self.service_is_up(service):
@@ -99,7 +109,11 @@ class SimpleScheduler(chance.ChanceScheduler):
             db.volume_update(context, volume_id, {'host': host,
                                                   'scheduled_at': now})
             return host
+
         results = db.service_get_all_volume_sorted(context)
+        if zone:
+            results = [(service, gigs) for (service, gigs) in results
+                       if service['availability_zone'] == zone]
         for result in results:
             (service, volume_gigabytes) = result
             if volume_gigabytes + volume_ref['size'] > FLAGS.max_gigabytes: