Fix capacity filter to allow oversubscription

Currently the capacity filter does not allow oversubscrition
if the free physical capacity is less than the new volume size.
This was based on the assumption that a new thinly provisioned
volume will be consumed right away. This assumption does not
allow us to take full advantage of thin provisioning.

The fix is to allow oversubscription if thin provisioning is
supported and max_over_subscription_ratio is greater than or
equal to 1. The free physical capacity will not be used to
compare with the new volume size for a backend that supports
oversubscription in thin provisioning. The oversubscription
ratio and virtual free capacity will still be used to decide
whether a backend can be chosen for thin provisioning.

Closes-Bug: #1458976
Change-Id: I4c8904445654db839c25ded420915f83c3756f94

diff --git a/cinder/scheduler/filters/capacity_filter.py b/cinder/scheduler/filters/capacity_filter.py
index 9d377bf62ae7518db2be5fdf7b7157d8465062ed..be13e67f08b3a64707c891ba1d405c2ad5df2aca 100644 (file)
--- a/cinder/scheduler/filters/capacity_filter.py
+++ b/cinder/scheduler/filters/capacity_filter.py
@@ -80,22 +80,13 @@ class CapacityFilter(filters.BaseHostFilter):
         msg_args = {"host": host_state.host,
                     "requested": volume_size,
                     "available": free}
-        if free < volume_size:
-            LOG.warning(_LW("Insufficient free space for volume creation "
-                            "on host %(host)s (requested / avail): "
-                            "%(requested)s/%(available)s"), msg_args)
-            return free >= volume_size
-        else:
-            LOG.debug("Space information for volume creation "
-                      "on host %(host)s (requested / avail): "
-                      "%(requested)s/%(available)s", msg_args)
 
         # Only evaluate using max_over_subscription_ratio if
         # thin_provisioning_support is True. Check if the ratio of
         # provisioned capacity over total capacity has exceeded over
         # subscription ratio.
         if (host_state.thin_provisioning_support and
-                host_state.max_over_subscription_ratio >= 1):
+                host_state.max_over_subscription_ratio > 1):
             provisioned_ratio = ((host_state.provisioned_capacity_gb +
                                   volume_size) / total)
             if provisioned_ratio >= host_state.max_over_subscription_ratio:
@@ -113,4 +104,14 @@ class CapacityFilter(filters.BaseHostFilter):
                 free_virtual = free * host_state.max_over_subscription_ratio
                 return free_virtual >= volume_size
 
-        return free >= volume_size
+        if free < volume_size:
+            LOG.warning(_LW("Insufficient free space for volume creation "
+                            "on host %(host)s (requested / avail): "
+                            "%(requested)s/%(available)s"), msg_args)
+            return False
+
+        LOG.debug("Space information for volume creation "
+                  "on host %(host)s (requested / avail): "
+                  "%(requested)s/%(available)s", msg_args)
+
+        return True

diff --git a/cinder/tests/unit/scheduler/test_host_filters.py b/cinder/tests/unit/scheduler/test_host_filters.py
index 592f2be564bf180c4a840913ac3091bbf88f9ee0..70e82696d4a27fb8eac39a7e27210b86645b80ca 100644 (file)
--- a/cinder/tests/unit/scheduler/test_host_filters.py
+++ b/cinder/tests/unit/scheduler/test_host_filters.py
@@ -162,6 +162,28 @@ class CapacityFilterTestCase(HostFiltersTestCase):
                                     'service': service})
         self.assertTrue(filt_cls.host_passes(host, filter_properties))
 
+    @mock.patch('cinder.utils.service_is_up')
+    def test_filter_over_subscription_less_than_1(self, _mock_serv_is_up):
+        _mock_serv_is_up.return_value = True
+        filt_cls = self.class_map['CapacityFilter']()
+        filter_properties = {'size': 200,
+                             'capabilities:thin_provisioning_support':
+                                 '<is> True',
+                             'capabilities:thick_provisioning_support':
+                                 '<is> False'}
+        service = {'disabled': False}
+        host = fakes.FakeHostState('host1',
+                                   {'total_capacity_gb': 500,
+                                    'free_capacity_gb': 100,
+                                    'provisioned_capacity_gb': 400,
+                                    'max_over_subscription_ratio': 0.8,
+                                    'reserved_percentage': 0,
+                                    'thin_provisioning_support': True,
+                                    'thick_provisioning_support': False,
+                                    'updated_at': None,
+                                    'service': service})
+        self.assertFalse(filt_cls.host_passes(host, filter_properties))
+
     @mock.patch('cinder.utils.service_is_up')
     def test_filter_over_subscription_fails(self, _mock_serv_is_up):
         _mock_serv_is_up.return_value = True
@@ -175,8 +197,8 @@ class CapacityFilterTestCase(HostFiltersTestCase):
         host = fakes.FakeHostState('host1',
                                    {'total_capacity_gb': 500,
                                     'free_capacity_gb': 200,
-                                    'provisioned_capacity_gb': 500,
-                                    'max_over_subscription_ratio': 1.0,
+                                    'provisioned_capacity_gb': 700,
+                                    'max_over_subscription_ratio': 1.5,
                                     'reserved_percentage': 5,
                                     'thin_provisioning_support': True,
                                     'thick_provisioning_support': False,
@@ -188,7 +210,7 @@ class CapacityFilterTestCase(HostFiltersTestCase):
     def test_filter_over_subscription_fails2(self, _mock_serv_is_up):
         _mock_serv_is_up.return_value = True
         filt_cls = self.class_map['CapacityFilter']()
-        filter_properties = {'size': 30,
+        filter_properties = {'size': 2000,
                              'capabilities:thin_provisioning_support':
                                  '<is> True',
                              'capabilities:thick_provisioning_support':
@@ -197,8 +219,8 @@ class CapacityFilterTestCase(HostFiltersTestCase):
         host = fakes.FakeHostState('host1',
                                    {'total_capacity_gb': 500,
                                     'free_capacity_gb': 30,
-                                    'provisioned_capacity_gb': 500,
-                                    'max_over_subscription_ratio': 1.0,
+                                    'provisioned_capacity_gb': 9000,
+                                    'max_over_subscription_ratio': 20,
                                     'reserved_percentage': 0,
                                     'thin_provisioning_support': True,
                                     'thick_provisioning_support': False,
@@ -219,7 +241,7 @@ class CapacityFilterTestCase(HostFiltersTestCase):
         host = fakes.FakeHostState('host1',
                                    {'total_capacity_gb': 500,
                                     'free_capacity_gb': 100,
-                                    'provisioned_capacity_gb': 500,
+                                    'provisioned_capacity_gb': 1000,
                                     'max_over_subscription_ratio': 2.0,
                                     'reserved_percentage': 5,
                                     'thin_provisioning_support': True,
@@ -264,8 +286,8 @@ class CapacityFilterTestCase(HostFiltersTestCase):
         service = {'disabled': False}
         host = fakes.FakeHostState('host1',
                                    {'total_capacity_gb': 500,
-                                    'free_capacity_gb': 100,
-                                    'provisioned_capacity_gb': 400,
+                                    'free_capacity_gb': 0,
+                                    'provisioned_capacity_gb': 800,
                                     'max_over_subscription_ratio': 2.0,
                                     'reserved_percentage': 5,
                                     'thin_provisioning_support': True,
@@ -296,6 +318,28 @@ class CapacityFilterTestCase(HostFiltersTestCase):
                                     'service': service})
         self.assertTrue(filt_cls.host_passes(host, filter_properties))
 
+    @mock.patch('cinder.utils.service_is_up')
+    def test_filter_reserved_thin_true_passes(self, _mock_serv_is_up):
+        _mock_serv_is_up.return_value = True
+        filt_cls = self.class_map['CapacityFilter']()
+        filter_properties = {'size': 100,
+                             'capabilities:thin_provisioning_support':
+                                 '<is> True',
+                             'capabilities:thick_provisioning_support':
+                                 '<is> False'}
+        service = {'disabled': False}
+        host = fakes.FakeHostState('host1',
+                                   {'total_capacity_gb': 500,
+                                    'free_capacity_gb': 80,
+                                    'provisioned_capacity_gb': 600,
+                                    'max_over_subscription_ratio': 2.0,
+                                    'reserved_percentage': 5,
+                                    'thin_provisioning_support': True,
+                                    'thick_provisioning_support': False,
+                                    'updated_at': None,
+                                    'service': service})
+        self.assertTrue(filt_cls.host_passes(host, filter_properties))
+
     @mock.patch('cinder.utils.service_is_up')
     def test_filter_reserved_thin_thick_true_fails2(self, _mock_serv_is_up):
         _mock_serv_is_up.return_value = True
@@ -309,7 +353,7 @@ class CapacityFilterTestCase(HostFiltersTestCase):
         host = fakes.FakeHostState('host1',
                                    {'total_capacity_gb': 500,
                                     'free_capacity_gb': 99,
-                                    'provisioned_capacity_gb': 400,
+                                    'provisioned_capacity_gb': 1000,
                                     'max_over_subscription_ratio': 2.0,
                                     'reserved_percentage': 5,
                                     'thin_provisioning_support': True,