NetApp: Add use-exact-size parameter when creating a LUN on ONTAP iSCSI

When a cinder volume is created the ontap backend fits the LUN to the
best geometry. It makes the image uploaded from a volume larger than
expected and a volume of larger size must be created from that image.
Using the use-exact-size parameter the backend does not fit to best
geometry, the image uploaded from that volume has the same size and a
volume of the same size may be created from that image.

Nevertheless this parameter is available only in Data ONTAP 9.1 (ontapi
version 1.110) and later.

Closes-Bug: #1731474
Change-Id: I0e21cbcb6effa1e72999580564099976511ca4a9

cinder/tests/unit/volume/drivers/netapp/dataontap/client/test_client_base.py

@@ -46,6 +46,7 @@ class NetAppBaseClientTestCase(test.TestCase):
         self.mock_object(client_base.Client, '_init_ssh_client')
         self.client = client_base.Client(**CONNECTION_INFO)
         self.client.connection = mock.MagicMock()
+        self.client.connection.get_api_version.return_value = (1, 100)
         self.client.ssh_client = mock.MagicMock()
         self.connection = self.client.connection
         self.fake_volume = six.text_type(uuid.uuid4())
@@ -86,7 +87,6 @@ class NetAppBaseClientTestCase(test.TestCase):
 
     def test_create_lun(self):
         expected_path = '/vol/%s/%s' % (self.fake_volume, self.fake_lun)
-
         with mock.patch.object(netapp_api.NaElement,
                                'create_node_with_children',
                                ) as mock_create_node:
@@ -105,6 +105,28 @@ class NetAppBaseClientTestCase(test.TestCase):
             self.connection.invoke_successfully.assert_called_once_with(
                 mock.ANY, True)
 
+    def test_create_lun_exact_size(self):
+        expected_path = '/vol/%s/%s' % (self.fake_volume, self.fake_lun)
+        self.connection.get_api_version.return_value = (1, 110)
+        with mock.patch.object(netapp_api.NaElement,
+                               'create_node_with_children',
+                               ) as mock_create_node:
+            self.client.create_lun(self.fake_volume,
+                                   self.fake_lun,
+                                   self.fake_size,
+                                   self.fake_metadata)
+
+            mock_create_node.assert_called_once_with(
+                'lun-create-by-size',
+                **{'path': expected_path,
+                   'size': self.fake_size,
+                   'ostype': self.fake_metadata['OsType'],
+                   'use-exact-size': 'true',
+                   'space-reservation-enabled':
+                   self.fake_metadata['SpaceReserved']})
+            self.connection.invoke_successfully.assert_called_once_with(
+                mock.ANY, True)
+
     def test_create_lun_with_qos_policy_group_name(self):
         expected_path = '/vol/%s/%s' % (self.fake_volume, self.fake_lun)
         expected_qos_group_name = 'qos_1'

cinder/volume/drivers/netapp/dataontap/client/client_base.py

@@ -94,11 +94,15 @@ class Client(object):
         """Issues API request for creating LUN on volume."""
 
         path = '/vol/%s/%s' % (volume_name, lun_name)
+        params = {'path': path, 'size': six.text_type(size),
+                  'ostype': metadata['OsType'],
+                  'space-reservation-enabled': metadata['SpaceReserved']}
+        version = self.get_ontapi_version()
+        if version >= (1, 110):
+            params['use-exact-size'] = 'true'
         lun_create = netapp_api.NaElement.create_node_with_children(
             'lun-create-by-size',
-            **{'path': path, 'size': six.text_type(size),
-               'ostype': metadata['OsType'],
-               'space-reservation-enabled': metadata['SpaceReserved']})
+            **params)
         if qos_policy_group_name:
             lun_create.add_new_child('qos-policy-group', qos_policy_group_name)
 

releasenotes/notes/netapp-ontap-use_exact_size-d03c90efbb8a30ac.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    Fixed bug #1731474 on NetApp Data ONTAP driver that was causing LUNs to be created
+    with larger size than requested. This fix requires version 9.1 of ONTAP
+    or later.