VNX: add option vnx_async_migrate

Before this fix, customers can disable async migration only by passing
`--metadata async_migrate=False` in volumes metadata. This fix adds an
option named `vnx_async_migrate` which could help set the default value
of async migration for whole backend. If customers don't pass in the
`async_migrate` in metadata, the value of this option will be used.

Change-Id: I8e59039da78ecc9fb5415a10ff2a7c26ee689171
Closes-bug: #1796825

cinder/tests/unit/volume/drivers/dell_emc/vnx/mocked_cinder.yaml

@@ -573,6 +573,9 @@ test_calc_migrate_and_provision_image_cache:
 test_calc_migrate_and_provision:
   volume: *volume_base
 
+test_calc_migrate_and_provision_default:
+  volume: *volume_base
+
 test_get_backend_qos_specs:
   volume:
     _type: 'volume'

cinder/tests/unit/volume/drivers/dell_emc/vnx/test_utils.py

@@ -205,6 +205,18 @@ class TestUtils(test_base.TestCase):
                          async_migrate)
         self.assertEqual(provision.name, 'THICK')
 
+    @res_mock.mock_driver_input
+    def test_calc_migrate_and_provision_default(self, mocked):
+        volume = mocked['volume']
+        volume.display_name = 'volume-ca86b9a0-d0d5-4267-8cd5-c62274056cc0'
+        async_migrate, provision = vnx_utils.calc_migrate_and_provision(
+            volume, default_async_migrate=False)
+        self.assertFalse(async_migrate)
+        self.assertEqual(provision.name, 'THICK')
+        async_migrate, provision = vnx_utils.calc_migrate_and_provision(
+            volume, default_async_migrate=True)
+        self.assertTrue(async_migrate)
+
     @ut_utils.patch_extra_specs({})
     @res_mock.mock_driver_input
     def test_get_backend_qos_specs(self, cinder_input):

cinder/volume/drivers/dell_emc/vnx/adapter.py

@@ -67,6 +67,7 @@ class CommonAdapter(replication.ReplicationAdapter):
         self.destroy_empty_sg = None
         self.itor_auto_dereg = None
         self.queue_path = None
+        self.async_migrate = None
 
     def _build_client_from_config(self, config, queue_path=None):
         return client.Client(
@@ -104,6 +105,7 @@ class CommonAdapter(replication.ReplicationAdapter):
         self.protocol = self.config.storage_protocol
         self.destroy_empty_sg = self.config.destroy_empty_storage_group
         self.itor_auto_dereg = self.config.initiator_auto_deregistration
+        self.async_migrate = self.config.vnx_async_migrate
         self.set_extra_spec_defaults()
 
     def _normalize_config(self):
@@ -349,7 +351,8 @@ class CommonAdapter(replication.ReplicationAdapter):
             volume_metadata['snapcopy'] = 'True'
             volume_metadata['async_migrate'] = 'False'
         else:
-            async_migrate, provision = utils.calc_migrate_and_provision(volume)
+            async_migrate, provision = utils.calc_migrate_and_provision(
+                volume, default_async_migrate=self.async_migrate)
             new_snap_name = (
                 utils.construct_snap_name(volume) if async_migrate else None)
             new_lun_id = emc_taskflow.create_volume_from_snapshot(
@@ -404,7 +407,8 @@ class CommonAdapter(replication.ReplicationAdapter):
             volume_metadata['snapcopy'] = 'True'
             volume_metadata['async_migrate'] = 'False'
         else:
-            async_migrate, provision = utils.calc_migrate_and_provision(volume)
+            async_migrate, provision = utils.calc_migrate_and_provision(
+                volume, default_async_migrate=self.async_migrate)
             new_lun_id = emc_taskflow.create_cloned_volume(
                 client=self.client,
                 snap_name=snap_name,
@@ -779,7 +783,8 @@ class CommonAdapter(replication.ReplicationAdapter):
 
     def delete_volume(self, volume):
         """Deletes an EMC volume."""
-        async_migrate = utils.is_async_migrate_enabled(volume)
+        async_migrate = utils.is_async_migrate_enabled(
+            volume, default=self.async_migrate)
         snap_copy = (utils.construct_snap_name(volume) if
                      utils.is_snapcopy_enabled(volume) else None)
         self.cleanup_lun_replication(volume)

cinder/volume/drivers/dell_emc/vnx/common.py

@@ -109,7 +109,17 @@ VNX_OPTS = [
                 default=False,
                 help='Force LUN creation even if '
                 'the full threshold of pool is reached. '
-                'By default, the value is False.')
+                'By default, the value is False.'),
+    cfg.BoolOpt('vnx_async_migrate',
+                default=True,
+                help='Always use asynchronous migration during volume cloning '
+                     'and creating from snapshot. As described in '
+                     'configuration doc, async migration has some '
+                     'constraints. Besides using metadata, customers could '
+                     'use this option to disable async migration. Be aware '
+                     'that `async_migrate` in metadata overrides this '
+                     'option when both are set. By default, the value is True.'
+                )
 ]
 
 CONF.register_opts(VNX_OPTS, group=configuration.SHARED_CONF_GROUP)

cinder/volume/drivers/dell_emc/vnx/driver.py

@@ -86,9 +86,11 @@ class VNXDriver(driver.ManageableVD,
                    under `destroy_empty_stroage_group` setting to `True`
           14.0.0 - Fix bug 1794646: failed to delete LUNs from backend due to
                    the temporary snapshots on them wasn't deleted.
+          14.0.1 - Fix bug 1796825, add an option to set default value for
+                   `async_migrate`.
     """
 
-    VERSION = '14.00.00'
+    VERSION = '14.00.01'
     VENDOR = 'Dell EMC'
     # ThirdPartySystems wiki page
     CI_WIKI_NAME = "EMC_VNX_CI"

cinder/volume/drivers/dell_emc/vnx/utils.py

@@ -257,7 +257,7 @@ def is_snapcopy_enabled(volume):
     return 'snapcopy' in meta and meta['snapcopy'].lower() == 'true'
 
 
-def is_async_migrate_enabled(volume):
+def is_async_migrate_enabled(volume, default=True):
     extra_specs = common.ExtraSpecs.from_volume(volume)
     if extra_specs.is_replication_enabled:
         # For replication-enabled volume, we should not use the async-cloned
@@ -266,8 +266,7 @@ def is_async_migrate_enabled(volume):
         return False
     meta = get_metadata(volume)
     if 'async_migrate' not in meta:
-        # Asynchronous migration is the default behavior now
+        return default
-        return True
     return 'async_migrate' in meta and meta['async_migrate'].lower() == 'true'
 
 
@@ -441,7 +440,7 @@ def is_image_cache_volume(volume):
     return False
 
 
-def calc_migrate_and_provision(volume):
+def calc_migrate_and_provision(volume, default_async_migrate=True):
     """Returns a tuple of async migrate and provision type.
 
     The first element is the flag whether to enable async migrate,
@@ -451,7 +450,8 @@ def calc_migrate_and_provision(volume):
         return False, storops.VNXProvisionEnum.THIN
     else:
         specs = common.ExtraSpecs.from_volume(volume)
-        return is_async_migrate_enabled(volume), specs.provision
+        return (is_async_migrate_enabled(volume, default_async_migrate),
+                specs.provision)
 
 
 def get_backend_qos_specs(volume):

doc/source/configuration/block-storage/drivers/dell-emc-vnx-driver.rst

@@ -433,6 +433,16 @@ Ignore pool full threshold
 If ``ignore_pool_full_threshold`` is set to ``True``, driver will force LUN
 creation even if the full threshold of pool is reached. Default to ``False``.
 
+Default value for async migration
+---------------------------------
+
+Option ``vnx_async_migrate`` is used to set the default value of async
+migration for the backend. The default value of this option is `True` if it
+isn't set in ``cinder.conf`` to preserve compatibility. If ``async_migrate`` is
+not set in metadata of volume, the value of this option will be used.
+Otherwise, ``async_migrate`` value in metadata will override the value of this
+option. For more detail, refer to `asynchronous migration support`_.
+
 Extra spec options
 ~~~~~~~~~~~~~~~~~~
 
@@ -791,8 +801,14 @@ as the default cloning method. The driver will return immediately after the
 migration session starts on the VNX, which dramatically reduces the time before
 a volume is available for use.
 
-To disable this feature, user can add ``--metadata async_migrate=False`` when
+To disable this feature, user needs to do any one of below actions:
-creating new volume from source.
+
+- Configure ``vnx_async_migrate = False`` for the backend in ``cinder.conf``,
+  then restart Cinder services.
+- Add ``--metadata async_migrate=False`` when creating new volume from source.
+
+Be aware, ``async_migrate`` in metadata overrides the option
+``vnx_async_migrate`` when both are set.
 
 **Constraints**
 

releasenotes/notes/vnx-add-async-migrate-option-0734164feeaecadc.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    Dell EMC VNX Driver: Fix `bug 1796825
+    <https://bugs.launchpad.net/cinder/+bug/1796825>`__, adding an option named
+    `vnx_async_migrate` to accept the default setting for async migration.