diff --git a/cinder/tests/unit/volume/drivers/dell_emc/unity/fake_exception.py b/cinder/tests/unit/volume/drivers/dell_emc/unity/fake_exception.py
index 6fa74ba8fcd..320bcf0a42c 100644
--- a/cinder/tests/unit/volume/drivers/dell_emc/unity/fake_exception.py
+++ b/cinder/tests/unit/volume/drivers/dell_emc/unity/fake_exception.py
@@ -18,35 +18,39 @@ class StoropsException(Exception):
     message = 'Storops Error.'
 
 
-class UnityLunNameInUseError(StoropsException):
+class UnityException(StoropsException):
     pass
 
 
-class UnityResourceNotFoundError(StoropsException):
+class UnityLunNameInUseError(UnityException):
     pass
 
 
-class UnitySnapNameInUseError(StoropsException):
+class UnityResourceNotFoundError(UnityException):
     pass
 
 
-class UnityDeleteAttachedSnapError(StoropsException):
+class UnitySnapNameInUseError(UnityException):
     pass
 
 
-class UnityResourceAlreadyAttachedError(StoropsException):
+class UnityDeleteAttachedSnapError(UnityException):
     pass
 
 
-class UnityPolicyNameInUseError(StoropsException):
+class UnityResourceAlreadyAttachedError(UnityException):
     pass
 
 
-class UnityNothingToModifyError(StoropsException):
+class UnityPolicyNameInUseError(UnityException):
     pass
 
 
-class UnityThinCloneLimitExceededError(StoropsException):
+class UnityNothingToModifyError(UnityException):
+    pass
+
+
+class UnityThinCloneLimitExceededError(UnityException):
     pass
 
 
@@ -82,15 +86,23 @@ class AdapterSetupError(Exception):
     pass
 
 
+class ReplicationManagerSetupError(Exception):
+    pass
+
+
 class HostDeleteIsCalled(Exception):
     pass
 
 
-class UnityThinCloneNotAllowedError(StoropsException):
+class UnityThinCloneNotAllowedError(UnityException):
     pass
 
 
-class SystemAPINotSupported(StoropsException):
+class SystemAPINotSupported(UnityException):
+    pass
+
+
+class UnityDeleteLunInReplicationError(UnityException):
     pass
 
 
diff --git a/cinder/tests/unit/volume/drivers/dell_emc/unity/test_adapter.py b/cinder/tests/unit/volume/drivers/dell_emc/unity/test_adapter.py
index bf3c7a89aeb..75a664fc864 100644
--- a/cinder/tests/unit/volume/drivers/dell_emc/unity/test_adapter.py
+++ b/cinder/tests/unit/volume/drivers/dell_emc/unity/test_adapter.py
@@ -26,6 +26,8 @@ from cinder.tests.unit.volume.drivers.dell_emc.unity \
     import fake_exception as ex
 from cinder.tests.unit.volume.drivers.dell_emc.unity import test_client
 from cinder.volume.drivers.dell_emc.unity import adapter
+from cinder.volume.drivers.dell_emc.unity import client
+from cinder.volume.drivers.dell_emc.unity import replication
 
 
 ########################
@@ -61,6 +63,8 @@ class MockConnector(object):
 class MockDriver(object):
     def __init__(self):
         self.configuration = mock.Mock(volume_dd_blocksize='1M')
+        self.replication_manager = MockReplicationManager()
+        self.protocol = 'iSCSI'
 
     @staticmethod
     def _connect_device(conn):
@@ -68,6 +72,27 @@ class MockDriver(object):
                 'device': {'path': 'dev'},
                 'conn': {'data': {}}}
 
+    def get_version(self):
+        return '1.0.0'
+
+
+class MockReplicationManager(object):
+    def __init__(self):
+        self.is_replication_configured = False
+        self.replication_devices = {}
+        self.active_backend_id = None
+        self.is_service_failed_over = None
+        self.default_device = None
+        self.active_adapter = None
+
+    def failover_service(self, backend_id):
+        if backend_id == 'default':
+            self.is_service_failed_over = False
+        elif backend_id == 'secondary_unity':
+            self.is_service_failed_over = True
+        else:
+            raise exception.VolumeBackendAPIException()
+
 
 class MockClient(object):
     def __init__(self):
@@ -232,6 +257,40 @@ class MockClient(object):
         if dest_pool_id == 'pool_3':
             return False
 
+    def get_remote_system(self, name=None):
+        if name == 'not-found-remote-system':
+            return None
+
+        return test_client.MockResource(_id='RS_1')
+
+    def get_replication_session(self, name=None):
+        if name == 'not-found-rep-session':
+            raise client.ClientReplicationError()
+
+        rep_session = test_client.MockResource(_id='rep_session_id_1')
+        rep_session.name = name
+        rep_session.src_resource_id = 'sv_1'
+        rep_session.dst_resource_id = 'sv_99'
+        return rep_session
+
+    def create_replication(self, src_lun, max_time_out_of_sync,
+                           dst_pool_id, remote_system):
+        if (src_lun.get_id() == 'sv_1' and max_time_out_of_sync == 60
+                and dst_pool_id == 'pool_1'
+                and remote_system.get_id() == 'RS_1'):
+            rep_session = test_client.MockResource(_id='rep_session_id_1')
+            rep_session.name = 'rep_session_name_1'
+            return rep_session
+        return None
+
+    def failover_replication(self, rep_session):
+        if rep_session.name != 'rep_session_name_1':
+            raise client.ClientReplicationError()
+
+    def failback_replication(self, rep_session):
+        if rep_session.name != 'rep_session_name_1':
+            raise client.ClientReplicationError()
+
 
 class MockLookupService(object):
     @staticmethod
@@ -253,6 +312,32 @@ class MockOSResource(mock.Mock):
             self.name = kwargs['name']
 
 
+def mock_replication_device(device_conf=None, serial_number=None,
+                            max_time_out_of_sync=None,
+                            destination_pool_id=None):
+    if device_conf is None:
+        device_conf = {
+            'backend_id': 'secondary_unity',
+            'san_ip': '2.2.2.2'
+        }
+
+    if serial_number is None:
+        serial_number = 'SECONDARY_UNITY_SN'
+
+    if max_time_out_of_sync is None:
+        max_time_out_of_sync = 60
+
+    if destination_pool_id is None:
+        destination_pool_id = 'pool_1'
+
+    rep_device = replication.ReplicationDevice(device_conf, MockDriver())
+    rep_device._adapter = mock_adapter(adapter.CommonAdapter)
+    rep_device._adapter._serial_number = serial_number
+    rep_device.max_time_out_of_sync = max_time_out_of_sync
+    rep_device._dst_pool = test_client.MockResource(_id=destination_pool_id)
+    return rep_device
+
+
 def mock_adapter(driver_clz):
     ret = driver_clz()
     ret._client = MockClient()
@@ -460,6 +545,8 @@ class CommonAdapterTest(test.TestCase):
         self.assertTrue(stats['thin_provisioning_support'])
         self.assertTrue(stats['compression_support'])
         self.assertTrue(stats['consistent_group_snapshot_enabled'])
+        self.assertFalse(stats['replication_enabled'])
+        self.assertEqual(0, len(stats['replication_targets']))
 
     def test_update_volume_stats(self):
         stats = self.adapter.update_volume_stats()
@@ -468,8 +555,26 @@ class CommonAdapterTest(test.TestCase):
         self.assertTrue(stats['thin_provisioning_support'])
         self.assertTrue(stats['thick_provisioning_support'])
         self.assertTrue(stats['consistent_group_snapshot_enabled'])
+        self.assertFalse(stats['replication_enabled'])
+        self.assertEqual(0, len(stats['replication_targets']))
         self.assertEqual(1, len(stats['pools']))
 
+    def test_get_replication_stats(self):
+        self.adapter.replication_manager.is_replication_configured = True
+        self.adapter.replication_manager.replication_devices = {
+            'secondary_unity': None
+        }
+
+        stats = self.adapter.update_volume_stats()
+        self.assertTrue(stats['replication_enabled'])
+        self.assertEqual(['secondary_unity'], stats['replication_targets'])
+
+        self.assertEqual(1, len(stats['pools']))
+        pool_stats = stats['pools'][0]
+        self.assertTrue(pool_stats['replication_enabled'])
+        self.assertEqual(['secondary_unity'],
+                         pool_stats['replication_targets'])
+
     def test_serial_number(self):
         self.assertEqual('CLIENT_SERIAL', self.adapter.serial_number)
 
@@ -1132,6 +1237,162 @@ class CommonAdapterTest(test.TestCase):
             mocked_delete.assert_called_once_with(cg_snap)
             self.assertEqual((None, None), ret)
 
+    def test_setup_replications(self):
+        secondary_device = mock_replication_device()
+
+        self.adapter.replication_manager.is_replication_configured = True
+        self.adapter.replication_manager.replication_devices = {
+            'secondary_unity': secondary_device
+        }
+        model_update = self.adapter.setup_replications(
+            test_client.MockResource(_id='sv_1'), {})
+
+        self.assertIn('replication_status', model_update)
+        self.assertEqual('enabled', model_update['replication_status'])
+
+        self.assertIn('replication_driver_data', model_update)
+        self.assertEqual('{"secondary_unity": "rep_session_name_1"}',
+                         model_update['replication_driver_data'])
+
+    def test_setup_replications_not_configured_replication(self):
+        model_update = self.adapter.setup_replications(
+            test_client.MockResource(_id='sv_1'), {})
+        self.assertEqual(0, len(model_update))
+
+    def test_setup_replications_raise(self):
+        secondary_device = mock_replication_device(
+            serial_number='not-found-remote-system')
+
+        self.adapter.replication_manager.is_replication_configured = True
+        self.adapter.replication_manager.replication_devices = {
+            'secondary_unity': secondary_device
+        }
+
+        self.assertRaises(exception.VolumeBackendAPIException,
+                          self.adapter.setup_replications,
+                          test_client.MockResource(_id='sv_1'),
+                          {})
+
+    @ddt.data({'failover_to': 'secondary_unity'},
+              {'failover_to': None})
+    @ddt.unpack
+    def test_failover(self, failover_to):
+        secondary_id = 'secondary_unity'
+        secondary_device = mock_replication_device()
+        self.adapter.replication_manager.is_replication_configured = True
+        self.adapter.replication_manager.replication_devices = {
+            secondary_id: secondary_device
+        }
+
+        volume = MockOSResource(
+            id='volume-id-1',
+            name='volume-name-1',
+            replication_driver_data='{"secondary_unity":"rep_session_name_1"}')
+        model_update = self.adapter.failover([volume],
+                                             secondary_id=failover_to)
+        self.assertEqual(3, len(model_update))
+        active_backend_id, volumes_update, groups_update = model_update
+        self.assertEqual(secondary_id, active_backend_id)
+        self.assertEqual([], groups_update)
+
+        self.assertEqual(1, len(volumes_update))
+        model_update = volumes_update[0]
+        self.assertIn('volume_id', model_update)
+        self.assertEqual('volume-id-1', model_update['volume_id'])
+        self.assertIn('updates', model_update)
+        self.assertEqual(
+            {'provider_id': 'sv_99',
+             'provider_location':
+                 'id^sv_99|system^SECONDARY_UNITY_SN|type^lun|version^None'},
+            model_update['updates'])
+        self.assertTrue(
+            self.adapter.replication_manager.is_service_failed_over)
+
+    def test_failover_raise(self):
+        secondary_id = 'secondary_unity'
+        secondary_device = mock_replication_device()
+        self.adapter.replication_manager.is_replication_configured = True
+        self.adapter.replication_manager.replication_devices = {
+            secondary_id: secondary_device
+        }
+
+        vol1 = MockOSResource(
+            id='volume-id-1',
+            name='volume-name-1',
+            replication_driver_data='{"secondary_unity":"rep_session_name_1"}')
+        vol2 = MockOSResource(
+            id='volume-id-2',
+            name='volume-name-2',
+            replication_driver_data='{"secondary_unity":"rep_session_name_2"}')
+        model_update = self.adapter.failover([vol1, vol2],
+                                             secondary_id=secondary_id)
+        active_backend_id, volumes_update, groups_update = model_update
+        self.assertEqual(secondary_id, active_backend_id)
+        self.assertEqual([], groups_update)
+
+        self.assertEqual(2, len(volumes_update))
+        m = volumes_update[0]
+        self.assertIn('volume_id', m)
+        self.assertEqual('volume-id-1', m['volume_id'])
+        self.assertIn('updates', m)
+        self.assertEqual(
+            {'provider_id': 'sv_99',
+             'provider_location':
+                 'id^sv_99|system^SECONDARY_UNITY_SN|type^lun|version^None'},
+            m['updates'])
+
+        m = volumes_update[1]
+        self.assertIn('volume_id', m)
+        self.assertEqual('volume-id-2', m['volume_id'])
+        self.assertIn('updates', m)
+        self.assertEqual({'replication_status': 'failover-error'},
+                         m['updates'])
+
+        self.assertTrue(
+            self.adapter.replication_manager.is_service_failed_over)
+
+    def test_failover_failback(self):
+        secondary_id = 'secondary_unity'
+        secondary_device = mock_replication_device()
+        self.adapter.replication_manager.is_replication_configured = True
+        self.adapter.replication_manager.replication_devices = {
+            secondary_id: secondary_device
+        }
+        default_device = mock_replication_device(
+            device_conf={
+                'backend_id': 'default',
+                'san_ip': '10.10.10.10'
+            }, serial_number='PRIMARY_UNITY_SN'
+        )
+        self.adapter.replication_manager.default_device = default_device
+        self.adapter.replication_manager.active_adapter = (
+            self.adapter.replication_manager.replication_devices[
+                secondary_id].adapter)
+        self.adapter.replication_manager.active_backend_id = secondary_id
+
+        volume = MockOSResource(
+            id='volume-id-1',
+            name='volume-name-1',
+            replication_driver_data='{"secondary_unity":"rep_session_name_1"}')
+        model_update = self.adapter.failover([volume],
+                                             secondary_id='default')
+        active_backend_id, volumes_update, groups_update = model_update
+        self.assertEqual('default', active_backend_id)
+        self.assertEqual([], groups_update)
+
+        self.assertEqual(1, len(volumes_update))
+        model_update = volumes_update[0]
+        self.assertIn('volume_id', model_update)
+        self.assertEqual('volume-id-1', model_update['volume_id'])
+        self.assertIn('updates', model_update)
+        self.assertEqual(
+            {'provider_id': 'sv_1',
+             'provider_location':
+                 'id^sv_1|system^PRIMARY_UNITY_SN|type^lun|version^None'},
+            model_update['updates'])
+        self.assertFalse(
+            self.adapter.replication_manager.is_service_failed_over)
+
 
 class FCAdapterTest(test.TestCase):
     def setUp(self):
diff --git a/cinder/tests/unit/volume/drivers/dell_emc/unity/test_client.py b/cinder/tests/unit/volume/drivers/dell_emc/unity/test_client.py
index 62cbba8167a..a4c593d5ce8 100644
--- a/cinder/tests/unit/volume/drivers/dell_emc/unity/test_client.py
+++ b/cinder/tests/unit/volume/drivers/dell_emc/unity/test_client.py
@@ -63,7 +63,7 @@ class MockResource(object):
     def get_id(self):
         return self._id
 
-    def delete(self):
+    def delete(self, force_snap_delete=None):
         if self.get_id() in ['snap_2']:
             raise ex.SnapDeleteIsCalled()
         elif self.get_id() == 'not_found':
@@ -72,6 +72,11 @@ class MockResource(object):
             raise ex.UnityDeleteAttachedSnapError()
         elif self.name == 'empty_host':
             raise ex.HostDeleteIsCalled()
+        elif self.get_id() == 'lun_in_replication':
+            if not force_snap_delete:
+                raise ex.UnityDeleteLunInReplicationError()
+        elif self.get_id() == 'lun_rep_session_1':
+            raise ex.UnityResourceNotFoundError()
 
     @property
     def pool(self):
@@ -207,6 +212,21 @@ class MockResource(object):
             return False
         return True
 
+    def replicate_with_dst_resource_provisioning(self, max_time_out_of_sync,
+                                                 dst_pool_id,
+                                                 remote_system=None,
+                                                 dst_lun_name=None):
+        return {'max_time_out_of_sync': max_time_out_of_sync,
+                'dst_pool_id': dst_pool_id,
+                'remote_system': remote_system,
+                'dst_lun_name': dst_lun_name}
+
+    def failover(self, sync=None):
+        return {'sync': sync}
+
+    def failback(self, force_full_copy=None):
+        return {'force_full_copy': force_full_copy}
+
 
 class MockResourceList(object):
     def __init__(self, names=None, ids=None):
@@ -327,6 +347,28 @@ class MockSystem(object):
     def get_io_limit_policy(name):
         return MockResource(name=name)
 
+    def get_remote_system(self, name=None):
+        if name == 'not-exist':
+            raise ex.UnityResourceNotFoundError()
+        else:
+            return {'name': name}
+
+    def get_replication_session(self, name=None,
+                                src_resource_id=None, dst_resource_id=None):
+        if name == 'not-exist':
+            raise ex.UnityResourceNotFoundError()
+        elif src_resource_id == 'lun_in_replication':
+            return [MockResource(name='rep_session')]
+        elif src_resource_id == 'lun_not_in_replication':
+            raise ex.UnityResourceNotFoundError()
+        elif src_resource_id == 'lun_in_multiple_replications':
+            return [MockResource(_id='lun_rep_session_1'),
+                    MockResource(_id='lun_rep_session_2')]
+        else:
+            return {'name': name,
+                    'src_resource_id': src_resource_id,
+                    'dst_resource_id': dst_resource_id}
+
 
 @mock.patch.object(client, 'storops', new='True')
 def get_client():
@@ -404,6 +446,15 @@ class ClientTest(unittest.TestCase):
         except ex.StoropsException:
             self.fail('not found error should be dealt with silently.')
 
+    def test_delete_lun_in_replication(self):
+        self.client.delete_lun('lun_in_replication')
+
+    @ddt.data({'lun_id': 'lun_not_in_replication'},
+              {'lun_id': 'lun_in_multiple_replications'})
+    @ddt.unpack
+    def test_delete_lun_replications(self, lun_id):
+        self.client.delete_lun_replications(lun_id)
+
     def test_get_lun_with_id(self):
         lun = self.client.get_lun('lun4')
         self.assertEqual('lun4', lun.get_id())
@@ -748,3 +799,61 @@ class ClientTest(unittest.TestCase):
             ret = self.client.filter_snaps_in_cg_snap('snap_cg_1')
             mocked_get.assert_called_once_with(snap_group='snap_cg_1')
             self.assertEqual(snaps, ret)
+
+    def test_create_replication(self):
+        remote_system = MockResource(_id='RS_1')
+        lun = MockResource(_id='sv_1')
+        called = self.client.create_replication(lun, 60, 'pool_1',
+                                                remote_system)
+        self.assertEqual(called['max_time_out_of_sync'], 60)
+        self.assertEqual(called['dst_pool_id'], 'pool_1')
+        self.assertIs(called['remote_system'], remote_system)
+
+    def test_get_remote_system(self):
+        called = self.client.get_remote_system(name='remote-unity')
+        self.assertEqual(called['name'], 'remote-unity')
+
+    def test_get_remote_system_not_exist(self):
+        called = self.client.get_remote_system(name='not-exist')
+        self.assertIsNone(called)
+
+    def test_get_replication_session(self):
+        called = self.client.get_replication_session(name='rep-name')
+        self.assertEqual(called['name'], 'rep-name')
+
+    def test_get_replication_session_not_exist(self):
+        self.assertRaises(client.ClientReplicationError,
+                          self.client.get_replication_session,
+                          name='not-exist')
+
+    def test_failover_replication(self):
+        rep_session = MockResource(_id='rep_id_1')
+        called = self.client.failover_replication(rep_session)
+        self.assertEqual(called['sync'], False)
+
+    def test_failover_replication_raise(self):
+        rep_session = MockResource(_id='rep_id_1')
+
+        def mock_failover(sync=None):
+            raise ex.UnityResourceNotFoundError()
+
+        rep_session.failover = mock_failover
+        self.assertRaises(client.ClientReplicationError,
+                          self.client.failover_replication,
+                          rep_session)
+
+    def test_failback_replication(self):
+        rep_session = MockResource(_id='rep_id_1')
+        called = self.client.failback_replication(rep_session)
+        self.assertEqual(called['force_full_copy'], True)
+
+    def test_failback_replication_raise(self):
+        rep_session = MockResource(_id='rep_id_1')
+
+        def mock_failback(force_full_copy=None):
+            raise ex.UnityResourceNotFoundError()
+
+        rep_session.failback = mock_failback
+        self.assertRaises(client.ClientReplicationError,
+                          self.client.failback_replication,
+                          rep_session)
diff --git a/cinder/tests/unit/volume/drivers/dell_emc/unity/test_driver.py b/cinder/tests/unit/volume/drivers/dell_emc/unity/test_driver.py
index 6b2eedc5886..7cb120bbe3d 100644
--- a/cinder/tests/unit/volume/drivers/dell_emc/unity/test_driver.py
+++ b/cinder/tests/unit/volume/drivers/dell_emc/unity/test_driver.py
@@ -32,7 +32,11 @@ from cinder.volume.drivers.dell_emc.unity import driver
 ########################
 
 class MockAdapter(object):
+    def __init__(self):
+        self.is_setup = False
+
     def do_setup(self, driver_object, configuration):
+        self.is_setup = True
         raise ex.AdapterSetupError()
 
     @staticmethod
@@ -135,6 +139,20 @@ class MockAdapter(object):
     def delete_group_snapshot(group_snapshot):
         return group_snapshot
 
+    def failover(self, volumes, secondary_id=None, groups=None):
+        return {'volumes': volumes,
+                'secondary_id': secondary_id,
+                'groups': groups}
+
+
+class MockReplicationManager(object):
+    def __init__(self):
+        self.active_adapter = MockAdapter()
+
+    def do_setup(self, d):
+        if isinstance(d, driver.UnityDriver):
+            raise ex.ReplicationManagerSetupError()
+
 
 ########################
 #
@@ -189,7 +207,7 @@ class UnityDriverTest(unittest.TestCase):
     def setUp(self):
         self.config = conf.Configuration(None)
         self.driver = driver.UnityDriver(configuration=self.config)
-        self.driver.adapter = MockAdapter()
+        self.driver.replication_manager = MockReplicationManager()
 
     def test_default_initialize(self):
         config = conf.Configuration(None)
@@ -208,6 +226,13 @@ class UnityDriverTest(unittest.TestCase):
         self.assertEqual(1, config.ssh_min_pool_conn)
         self.assertEqual(5, config.ssh_max_pool_conn)
         self.assertEqual('iSCSI', iscsi_driver.protocol)
+        self.assertIsNone(iscsi_driver.active_backend_id)
+
+    def test_initialize_with_active_backend_id(self):
+        config = conf.Configuration(None)
+        iscsi_driver = driver.UnityDriver(configuration=config,
+                                          active_backend_id='secondary_unity')
+        self.assertEqual('secondary_unity', iscsi_driver.active_backend_id)
 
     def test_fc_initialize(self):
         config = conf.Configuration(None)
@@ -219,7 +244,7 @@ class UnityDriverTest(unittest.TestCase):
         def f():
             self.driver.do_setup(None)
 
-        self.assertRaises(ex.AdapterSetupError, f)
+        self.assertRaises(ex.ReplicationManagerSetupError, f)
 
     def test_create_volume(self):
         volume = self.get_volume()
@@ -422,3 +447,12 @@ class UnityDriverTest(unittest.TestCase):
         ret = self.driver.delete_group_snapshot(self.get_context(), cg_snap,
                                                 None)
         self.assertEqual(ret, cg_snap)
+
+    def test_failover_host(self):
+        volume = self.get_volume()
+        called = self.driver.failover_host(None, [volume],
+                                           secondary_id='secondary_unity',
+                                           groups=None)
+        self.assertListEqual(called['volumes'], [volume])
+        self.assertEqual('secondary_unity', called['secondary_id'])
+        self.assertIsNone(called['groups'])
diff --git a/cinder/tests/unit/volume/drivers/dell_emc/unity/test_replication.py b/cinder/tests/unit/volume/drivers/dell_emc/unity/test_replication.py
new file mode 100644
index 00000000000..f81a1242b37
--- /dev/null
+++ b/cinder/tests/unit/volume/drivers/dell_emc/unity/test_replication.py
@@ -0,0 +1,362 @@
+# Copyright (c) 2016 - 2019 Dell Inc. or its subsidiaries.
+# All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+import unittest
+
+import ddt
+from mock import mock
+
+from cinder import exception
+from cinder.volume import configuration as conf
+from cinder.volume.drivers.dell_emc.unity import adapter as unity_adapter
+from cinder.volume.drivers.dell_emc.unity import driver
+from cinder.volume.drivers.dell_emc.unity import replication
+from cinder.volume.drivers.san.san import san_opts
+
+
+@ddt.ddt
+class UnityReplicationTest(unittest.TestCase):
+    @ddt.data({'version': '1.0.0', 'protocol': 'FC',
+               'expected': unity_adapter.FCAdapter},
+              {'version': '2.0.0', 'protocol': 'iSCSI',
+               'expected': unity_adapter.ISCSIAdapter})
+    @ddt.unpack
+    def test_init_adapter(self, version, protocol, expected):
+        a = replication.init_adapter(version, protocol)
+        self.assertIsInstance(a, expected)
+        self.assertEqual(version, a.version)
+
+
+@ddt.ddt
+class UnityReplicationDeviceTest(unittest.TestCase):
+    def setUp(self):
+        self.config = conf.Configuration(san_opts,
+                                         config_group='unity-backend')
+        self.config.san_ip = '1.1.1.1'
+        self.config.san_login = 'user1'
+        self.config.san_password = 'password1'
+        self.driver = driver.UnityDriver(configuration=self.config)
+
+        conf_dict = {'backend_id': 'secondary_unity', 'san_ip': '2.2.2.2'}
+        self.mock_adapter = mock.MagicMock(is_setup=False)
+
+        def mock_do_setup(*args):
+            self.mock_adapter.is_setup = True
+
+        self.mock_adapter.do_setup = mock.MagicMock(side_effect=mock_do_setup)
+        with mock.patch('cinder.volume.drivers.dell_emc.unity.'
+                        'replication.init_adapter',
+                        return_value=self.mock_adapter):
+            self.replication_device = replication.ReplicationDevice(
+                conf_dict, self.driver)
+
+    @ddt.data(
+        {
+            'conf_dict': {
+                'backend_id': 'secondary_unity',
+                'san_ip': '2.2.2.2'
+            },
+            'expected': [
+                'secondary_unity', '2.2.2.2', 'user1', 'password1', 60
+            ]
+        },
+        {
+            'conf_dict': {
+                'backend_id': 'secondary_unity',
+                'san_ip': '2.2.2.2',
+                'san_login': 'user2',
+                'san_password': 'password2',
+                'max_time_out_of_sync': 180
+            },
+            'expected': [
+                'secondary_unity', '2.2.2.2', 'user2', 'password2', 180
+            ]
+        },
+    )
+    @ddt.unpack
+    def test_init(self, conf_dict, expected):
+        self.driver.configuration.replication_device = conf_dict
+        device = replication.ReplicationDevice(conf_dict, self.driver)
+
+        self.assertListEqual(
+            [device.backend_id, device.san_ip, device.san_login,
+             device.san_password, device.max_time_out_of_sync],
+            expected)
+
+        self.assertIs(self.driver, device.driver)
+
+    @ddt.data(
+        {
+            'conf_dict': {'san_ip': '2.2.2.2'},
+        },
+        {
+            'conf_dict': {'backend_id': '  ', 'san_ip': '2.2.2.2'},
+        },
+        {
+            'conf_dict': {'backend_id': 'secondary_unity'},
+        },
+        {
+            'conf_dict': {'backend_id': 'secondary_unity', 'san_ip': '  '},
+        },
+        {
+            'conf_dict': {
+                'backend_id': 'secondary_unity',
+                'san_ip': '2.2.2.2',
+                'san_login': 'user2',
+                'san_password': 'password2',
+                'max_time_out_of_sync': 'NOT_A_NUMBER'
+            },
+        },
+    )
+    @ddt.unpack
+    def test_init_raise(self, conf_dict):
+        self.driver.configuration.replication_device = conf_dict
+        self.assertRaisesRegexp(exception.InvalidConfigurationValue,
+                                'Value .* is not valid for configuration '
+                                'option "unity-backend.replication_device"',
+                                replication.ReplicationDevice,
+                                conf_dict, self.driver)
+
+    @ddt.data(
+        {
+            'conf_dict': {
+                'backend_id': 'secondary_unity',
+                'san_ip': '2.2.2.2'
+            },
+            'expected': [
+                '2.2.2.2', 'user1', 'password1'
+            ]
+        },
+        {
+            'conf_dict': {
+                'backend_id': 'secondary_unity',
+                'san_ip': '2.2.2.2',
+                'san_login': 'user2',
+                'san_password': 'password2',
+                'max_time_out_of_sync': 180
+            },
+            'expected': [
+                '2.2.2.2', 'user2', 'password2'
+            ]
+        },
+    )
+    @ddt.unpack
+    def test_device_conf(self, conf_dict, expected):
+        self.driver.configuration.replication_device = conf_dict
+        device = replication.ReplicationDevice(conf_dict, self.driver)
+
+        c = device.device_conf
+        self.assertListEqual([c.san_ip, c.san_login, c.san_password],
+                             expected)
+
+    def test_setup_adapter(self):
+        self.replication_device.setup_adapter()
+
+        # Not call adapter.do_setup after initial setup done.
+        self.replication_device.setup_adapter()
+
+        self.mock_adapter.do_setup.assert_called_once()
+
+    def test_setup_adapter_fail(self):
+        def f(*args):
+            raise exception.VolumeBackendAPIException('adapter setup failed')
+
+        self.mock_adapter.do_setup = mock.MagicMock(side_effect=f)
+
+        with self.assertRaises(exception.VolumeBackendAPIException):
+            self.replication_device.setup_adapter()
+
+    def test_adapter(self):
+        self.assertIs(self.mock_adapter, self.replication_device.adapter)
+        self.mock_adapter.do_setup.assert_called_once()
+
+    def test_destination_pool(self):
+        self.mock_adapter.storage_pools_map = {'pool-1': 'pool-1'}
+        self.assertEqual('pool-1', self.replication_device.destination_pool)
+
+
+@ddt.ddt
+class UnityReplicationManagerTest(unittest.TestCase):
+    def setUp(self):
+        self.config = conf.Configuration(san_opts,
+                                         config_group='unity-backend')
+        self.config.san_ip = '1.1.1.1'
+        self.config.san_login = 'user1'
+        self.config.san_password = 'password1'
+        self.config.replication_device = [
+            {'backend_id': 'secondary_unity', 'san_ip': '2.2.2.2'}
+        ]
+        self.driver = driver.UnityDriver(configuration=self.config)
+
+        self.replication_manager = replication.ReplicationManager()
+
+    @mock.patch('cinder.volume.drivers.dell_emc.unity.'
+                'replication.ReplicationDevice.setup_adapter')
+    def test_do_setup(self, mock_setup_adapter):
+        self.replication_manager.do_setup(self.driver)
+        calls = [mock.call(), mock.call()]
+
+        default_device = self.replication_manager.default_device
+        self.assertEqual('1.1.1.1', default_device.san_ip)
+        self.assertEqual('user1', default_device.san_login)
+        self.assertEqual('password1', default_device.san_password)
+
+        devices = self.replication_manager.replication_devices
+        self.assertEqual(1, len(devices))
+        self.assertIn('secondary_unity', devices)
+        rep_device = devices['secondary_unity']
+        self.assertEqual('2.2.2.2', rep_device.san_ip)
+        self.assertEqual('user1', rep_device.san_login)
+        self.assertEqual('password1', rep_device.san_password)
+
+        self.assertTrue(self.replication_manager.is_replication_configured)
+
+        self.assertTrue(
+            self.replication_manager.active_backend_id is None
+            or self.replication_manager.active_backend_id == 'default')
+
+        self.assertFalse(self.replication_manager.is_service_failed_over)
+
+        active_adapter = self.replication_manager.active_adapter
+        calls.append(mock.call())
+        self.assertIs(default_device.adapter, active_adapter)
+        calls.append(mock.call())
+        mock_setup_adapter.assert_has_calls(calls)
+
+    @mock.patch('cinder.volume.drivers.dell_emc.unity.'
+                'replication.ReplicationDevice.setup_adapter')
+    def test_do_setup_replication_not_configured(self, mock_setup_adapter):
+        self.driver.configuration.replication_device = None
+
+        self.replication_manager.do_setup(self.driver)
+        calls = [mock.call()]
+
+        default_device = self.replication_manager.default_device
+        self.assertEqual('1.1.1.1', default_device.san_ip)
+        self.assertEqual('user1', default_device.san_login)
+        self.assertEqual('password1', default_device.san_password)
+
+        devices = self.replication_manager.replication_devices
+        self.assertEqual(0, len(devices))
+
+        self.assertFalse(self.replication_manager.is_replication_configured)
+
+        self.assertTrue(
+            self.replication_manager.active_backend_id is None
+            or self.replication_manager.active_backend_id == 'default')
+
+        self.assertFalse(self.replication_manager.is_service_failed_over)
+
+        active_adapter = self.replication_manager.active_adapter
+        calls.append(mock.call())
+        self.assertIs(default_device.adapter, active_adapter)
+        calls.append(mock.call())
+
+        mock_setup_adapter.assert_has_calls(calls)
+
+    @mock.patch('cinder.volume.drivers.dell_emc.unity.'
+                'replication.ReplicationDevice.setup_adapter')
+    def test_do_setup_failed_over(self, mock_setup_adapter):
+        self.driver = driver.UnityDriver(configuration=self.config,
+                                         active_backend_id='secondary_unity')
+
+        self.replication_manager.do_setup(self.driver)
+        calls = [mock.call()]
+
+        default_device = self.replication_manager.default_device
+        self.assertEqual('1.1.1.1', default_device.san_ip)
+        self.assertEqual('user1', default_device.san_login)
+        self.assertEqual('password1', default_device.san_password)
+
+        devices = self.replication_manager.replication_devices
+        self.assertEqual(1, len(devices))
+        self.assertIn('secondary_unity', devices)
+        rep_device = devices['secondary_unity']
+        self.assertEqual('2.2.2.2', rep_device.san_ip)
+        self.assertEqual('user1', rep_device.san_login)
+        self.assertEqual('password1', rep_device.san_password)
+
+        self.assertTrue(self.replication_manager.is_replication_configured)
+
+        self.assertEqual('secondary_unity',
+                         self.replication_manager.active_backend_id)
+
+        self.assertTrue(self.replication_manager.is_service_failed_over)
+
+        active_adapter = self.replication_manager.active_adapter
+        calls.append(mock.call())
+        self.assertIs(rep_device.adapter, active_adapter)
+        calls.append(mock.call())
+
+        mock_setup_adapter.assert_has_calls(calls)
+
+    @ddt.data(
+        {
+            'rep_device': [{
+                'backend_id': 'default', 'san_ip': '2.2.2.2'
+            }]
+        },
+        {
+            'rep_device': [{
+                'backend_id': 'secondary_unity', 'san_ip': '2.2.2.2'
+            }, {
+                'backend_id': 'default', 'san_ip': '3.3.3.3'
+            }]
+        },
+        {
+            'rep_device': [{
+                'backend_id': 'secondary_unity', 'san_ip': '2.2.2.2'
+            }, {
+                'backend_id': 'third_unity', 'san_ip': '3.3.3.3'
+            }]
+        },
+    )
+    @ddt.unpack
+    @mock.patch('cinder.volume.drivers.dell_emc.unity.'
+                'replication.ReplicationDevice.setup_adapter')
+    def test_do_setup_raise_invalid_rep_device(self, mock_setup_adapter,
+                                               rep_device):
+        self.driver.configuration.replication_device = rep_device
+
+        self.assertRaises(exception.InvalidConfigurationValue,
+                          self.replication_manager.do_setup,
+                          self.driver)
+
+    @mock.patch('cinder.volume.drivers.dell_emc.unity.'
+                'replication.ReplicationDevice.setup_adapter')
+    def test_do_setup_raise_invalid_active_backend_id(self,
+                                                      mock_setup_adapter):
+        self.driver = driver.UnityDriver(configuration=self.config,
+                                         active_backend_id='third_unity')
+
+        self.assertRaises(exception.InvalidConfigurationValue,
+                          self.replication_manager.do_setup,
+                          self.driver)
+
+    @mock.patch('cinder.volume.drivers.dell_emc.unity.'
+                'replication.ReplicationDevice.setup_adapter')
+    def test_failover_service(self, mock_setup_adapter):
+
+        self.assertIsNone(self.replication_manager.active_backend_id)
+
+        self.replication_manager.do_setup(self.driver)
+        self.replication_manager.active_adapter
+
+        self.assertEqual('default',
+                         self.replication_manager.active_backend_id)
+
+        self.replication_manager.failover_service('secondary_unity')
+        self.assertEqual('secondary_unity',
+                         self.replication_manager.active_backend_id)
diff --git a/cinder/volume/drivers/dell_emc/unity/adapter.py b/cinder/volume/drivers/dell_emc/unity/adapter.py
index 755eb8fcf13..627d3bfd23f 100644
--- a/cinder/volume/drivers/dell_emc/unity/adapter.py
+++ b/cinder/volume/drivers/dell_emc/unity/adapter.py
@@ -61,6 +61,7 @@ class VolumeParams(object):
         self._is_thick = None
         self._is_compressed = None
         self._is_in_cg = None
+        self._is_replication_enabled = None
 
     @property
     def volume_id(self):
@@ -149,6 +150,13 @@ class VolumeParams(object):
             return self._volume.group_id
         return None
 
+    @property
+    def is_replication_enabled(self):
+        if self._is_replication_enabled is None:
+            value = utils.get_extra_spec(self._volume, 'replication_enabled')
+            self._is_replication_enabled = value == '<is> True'
+        return self._is_replication_enabled
+
     def __eq__(self, other):
         return (self.volume_id == other.volume_id and
                 self.name == other.name and
@@ -157,7 +165,8 @@ class VolumeParams(object):
                 self.is_thick == other.is_thick and
                 self.is_compressed == other.is_compressed and
                 self.is_in_cg == other.is_in_cg and
-                self.cg_id == other.cg_id)
+                self.cg_id == other.cg_id and
+                self.is_replication_enabled == other.is_replication_enabled)
 
 
 class CommonAdapter(object):
@@ -166,6 +175,7 @@ class CommonAdapter(object):
     driver_volume_type = 'unknown'
 
     def __init__(self, version=None):
+        self.is_setup = False
         self.version = version
         self.driver = None
         self.config = None
@@ -185,10 +195,17 @@ class CommonAdapter(object):
         self.allowed_ports = None
         self.remove_empty_host = False
         self.to_lock_host = False
+        self.replication_manager = None
 
     def do_setup(self, driver, conf):
+        """Sets up the attributes of adapter.
+
+        :param driver: the unity driver.
+        :param conf: the driver configurations.
+        """
         self.driver = driver
         self.config = self.normalize_config(conf)
+        self.replication_manager = driver.replication_manager
         self.configured_pool_names = self.config.unity_storage_pool_names
         self.reserved_percentage = self.config.reserved_percentage
         self.max_over_subscription_ratio = (
@@ -222,6 +239,8 @@ class CommonAdapter(object):
         persist_path = os.path.join(cfg.CONF.state_path, 'unity', folder_name)
         storops.TCHelper.set_up(persist_path)
 
+        self.is_setup = True
+
     def normalize_config(self, config):
         config.unity_storage_pool_names = utils.remove_empty(
             '%s.unity_storage_pool_names' % config.config_group,
@@ -298,15 +317,39 @@ class CommonAdapter(object):
         valid_names = utils.validate_pool_names(names, array_pools.name)
         return {p.name: p for p in array_pools if p.name in valid_names}
 
-    def makeup_model(self, lun, is_snap_lun=False):
+    def makeup_model(self, lun_id, is_snap_lun=False):
         lun_type = 'snap_lun' if is_snap_lun else 'lun'
-        location = self._build_provider_location(lun_id=lun.get_id(),
+        location = self._build_provider_location(lun_id=lun_id,
                                                  lun_type=lun_type)
         return {
             'provider_location': location,
-            'provider_id': lun.get_id()
+            'provider_id': lun_id
         }
 
+    def setup_replications(self, lun, model_update):
+        if not self.replication_manager.is_replication_configured:
+            LOG.debug('Replication device not configured, '
+                      'skip setting up replication for lun %s',
+                      lun.name)
+            return model_update
+
+        rep_data = {}
+        rep_devices = self.replication_manager.replication_devices
+        for backend_id, dst in rep_devices.items():
+            remote_serial_number = dst.adapter.serial_number
+            LOG.debug('Setting up replication to remote system %s',
+                      remote_serial_number)
+            remote_system = self.client.get_remote_system(remote_serial_number)
+            if remote_system is None:
+                raise exception.VolumeBackendAPIException(
+                    data=_('Setup replication to remote system %s failed.'
+                           'Cannot find it.') % remote_serial_number)
+            rep_session = self.client.create_replication(
+                lun, dst.max_time_out_of_sync,
+                dst.destination_pool.get_id(), remote_system)
+            rep_data[backend_id] = rep_session.name
+        return utils.enable_replication_status(model_update, rep_data)
+
     def create_volume(self, volume):
         """Creates a volume.
 
@@ -321,13 +364,15 @@ class CommonAdapter(object):
             'io_limit_policy': params.io_limit_policy,
             'is_thick': params.is_thick,
             'is_compressed': params.is_compressed,
-            'cg_id': params.cg_id
+            'cg_id': params.cg_id,
+            'is_replication_enabled': params.is_replication_enabled
         }
 
         LOG.info('Create Volume: %(name)s, size: %(size)s, description: '
                  '%(description)s, pool: %(pool)s, io limit policy: '
                  '%(io_limit_policy)s, thick: %(is_thick)s, '
-                 'compressed: %(is_compressed)s, cg_group: %(cg_id)s.',
+                 'compressed: %(is_compressed)s, cg_group: %(cg_id)s, '
+                 'replication_enabled: %(is_replication_enabled)s.',
                  log_params)
 
         lun = self.client.create_lun(
@@ -338,12 +383,17 @@ class CommonAdapter(object):
             io_limit_policy=params.io_limit_policy,
             is_thin=False if params.is_thick else None,
             is_compressed=params.is_compressed)
+
         if params.cg_id:
             LOG.debug('Adding lun %(lun)s to cg %(cg)s.',
                       {'lun': lun.get_id(), 'cg': params.cg_id})
             self.client.update_cg(params.cg_id, [lun.get_id()], ())
 
-        return self.makeup_model(lun)
+        model_update = self.makeup_model(lun.get_id())
+
+        if params.is_replication_enabled:
+            model_update = self.setup_replications(lun, model_update)
+        return model_update
 
     def delete_volume(self, volume):
         lun_id = self.get_lun_id(volume)
@@ -474,6 +524,10 @@ class CommonAdapter(object):
             'volume_backend_name': self.volume_backend_name,
             'storage_protocol': self.protocol,
             'pools': self.get_pools_stats(),
+            'replication_enabled':
+                self.replication_manager.is_replication_configured,
+            'replication_targets':
+                list(self.replication_manager.replication_devices),
         }
 
     def get_pools_stats(self):
@@ -499,7 +553,11 @@ class CommonAdapter(object):
             'compression_support': pool.is_all_flash,
             'max_over_subscription_ratio': (
                 self.max_over_subscription_ratio),
-            'multiattach': True
+            'multiattach': True,
+            'replication_enabled':
+                self.replication_manager.is_replication_configured,
+            'replication_targets':
+                list(self.replication_manager.replication_devices),
         }
 
     def get_lun_id(self, volume):
@@ -737,9 +795,13 @@ class CommonAdapter(object):
 
     def create_volume_from_snapshot(self, volume, snapshot):
         snap = self.client.get_snap(snapshot.name)
-        return self.makeup_model(
-            self._thin_clone(VolumeParams(self, volume), snap),
-            is_snap_lun=True)
+        params = VolumeParams(self, volume)
+        lun = self._thin_clone(params, snap)
+        model_update = self.makeup_model(lun.get_id(), is_snap_lun=True)
+
+        if params.is_replication_enabled:
+            model_update = self.setup_replications(lun, model_update)
+        return model_update
 
     def create_cloned_volume(self, volume, src_vref):
         """Creates cloned volume.
@@ -777,10 +839,15 @@ class CommonAdapter(object):
                           '%(name)s is attached: %(attach)s.',
                           {'name': src_vref.name,
                            'attach': src_vref.volume_attachment})
-                return self.makeup_model(lun)
+                model_update = self.makeup_model(lun.get_id())
             else:
                 lun = self._thin_clone(vol_params, src_snap, src_lun=src_lun)
-                return self.makeup_model(lun, is_snap_lun=True)
+                model_update = self.makeup_model(lun.get_id(),
+                                                 is_snap_lun=True)
+
+            if vol_params.is_replication_enabled:
+                model_update = self.setup_replications(lun, model_update)
+            return model_update
 
     def get_pool_name(self, volume):
         return self.client.get_pool_name(volume.name)
@@ -925,6 +992,75 @@ class CommonAdapter(object):
         self.client.delete_snap(cg_snap)
         return None, None
 
+    @cinder_utils.trace
+    def failover(self, volumes, secondary_id=None, groups=None):
+        # TODO(ryan) support group failover after group bp merges
+        # https://review.openstack.org/#/c/574119/
+
+        if secondary_id is None:
+            LOG.debug('No secondary specified when failover. '
+                      'Randomly choose a secondary')
+            secondary_id = random.choice(
+                list(self.replication_manager.replication_devices))
+            LOG.debug('Chose %s as secondary', secondary_id)
+
+        is_failback = secondary_id == 'default'
+
+        def _failover_or_back(volume):
+            LOG.debug('Failing over volume: %(vol)s to secondary id: '
+                      '%(sec_id)s', vol=volume.name, sec_id=secondary_id)
+            model_update = {
+                'volume_id': volume.id,
+                'updates': {}
+            }
+
+            if not volume.replication_driver_data:
+                LOG.error('Empty replication_driver_data of volume: %s, '
+                          'replication session name should be in it.',
+                          volume.name)
+                return utils.error_replication_status(model_update)
+            rep_data = utils.load_replication_data(
+                volume.replication_driver_data)
+
+            if is_failback:
+                # Failback executed on secondary backend which is currently
+                # active.
+                _adapter = self.replication_manager.default_device.adapter
+                _client = self.replication_manager.active_adapter.client
+                rep_name = rep_data[self.replication_manager.active_backend_id]
+            else:
+                # Failover executed on secondary backend because primary could
+                # die.
+                _adapter = self.replication_manager.replication_devices[
+                    secondary_id].adapter
+                _client = _adapter.client
+                rep_name = rep_data[secondary_id]
+
+            try:
+                rep_session = _client.get_replication_session(name=rep_name)
+
+                if is_failback:
+                    _client.failback_replication(rep_session)
+                    new_model = _adapter.makeup_model(
+                        rep_session.src_resource_id)
+                else:
+                    _client.failover_replication(rep_session)
+                    new_model = _adapter.makeup_model(
+                        rep_session.dst_resource_id)
+
+                model_update['updates'].update(new_model)
+                self.replication_manager.failover_service(secondary_id)
+                return model_update
+            except client.ClientReplicationError as ex:
+                LOG.error('Failover failed, volume: %(vol)s, secondary id: '
+                          '%(sec_id)s, error: %(err)s',
+                          vol=volume.name, sec_id=secondary_id, err=ex)
+                return utils.error_replication_status(model_update)
+
+        return (secondary_id,
+                [_failover_or_back(volume) for volume in volumes],
+                [])
+
 
 class ISCSIAdapter(CommonAdapter):
     protocol = PROTOCOL_ISCSI
diff --git a/cinder/volume/drivers/dell_emc/unity/client.py b/cinder/volume/drivers/dell_emc/unity/client.py
index 74b0204dd07..f054c4ac286 100644
--- a/cinder/volume/drivers/dell_emc/unity/client.py
+++ b/cinder/volume/drivers/dell_emc/unity/client.py
@@ -104,10 +104,47 @@ class UnityClient(object):
         """
         try:
             lun = self.system.get_lun(_id=lun_id)
-            lun.delete()
         except storops_ex.UnityResourceNotFoundError:
-            LOG.debug("LUN %s doesn't exist. Deletion is not needed.",
+            LOG.debug("Cannot get LUN %s from unity. Do nothing.", lun_id)
+            return
+
+        def _delete_lun_if_exist(force_snap_delete=False):
+            """Deletes LUN, skip if it doesn't exist."""
+            try:
+                lun.delete(force_snap_delete=force_snap_delete)
+            except storops_ex.UnityResourceNotFoundError:
+                LOG.debug("LUN %s doesn't exist. Deletion is not needed.",
+                          lun_id)
+
+        try:
+            _delete_lun_if_exist()
+        except storops_ex.UnityDeleteLunInReplicationError:
+            LOG.info("LUN %s is participating in replication sessions. "
+                     "Delete replication sessions first",
+                     lun_id)
+            self.delete_lun_replications(lun_id)
+
+            # It could fail if not pass in force_snap_delete when
+            # deleting the lun immediately after
+            # deleting the replication sessions.
+            _delete_lun_if_exist(force_snap_delete=True)
+
+    def delete_lun_replications(self, lun_id):
+        LOG.debug("Deleting all the replication sessions which are from "
+                  "lun %s", lun_id)
+        try:
+            rep_sessions = self.system.get_replication_session(
+                src_resource_id=lun_id)
+        except storops_ex.UnityResourceNotFoundError:
+            LOG.debug("No replication session found from lun %s. Do nothing.",
                       lun_id)
+        else:
+            for session in rep_sessions:
+                try:
+                    session.delete()
+                except storops_ex.UnityResourceNotFoundError:
+                    LOG.debug("Replication session %s doesn't exist. "
+                              "Skip the deletion.", session.get_id())
 
     def get_lun(self, lun_id=None, name=None):
         """Gets LUN on the Unity system.
@@ -388,3 +425,86 @@ class UnityClient(object):
 
     def filter_snaps_in_cg_snap(self, cg_snap_id):
         return self.system.get_snap(snap_group=cg_snap_id).list
+
+    @staticmethod
+    def create_replication(src_lun, max_time_out_of_sync,
+                           dst_pool_id, remote_system):
+        """Creates a new lun on remote system and sets up replication to it."""
+        return src_lun.replicate_with_dst_resource_provisioning(
+            max_time_out_of_sync, dst_pool_id, remote_system=remote_system,
+            dst_lun_name=src_lun.name)
+
+    def get_remote_system(self, name=None):
+        """Gets remote system on the Unity system.
+
+        :param name: remote system name.
+        :return: remote system.
+        """
+        try:
+            return self.system.get_remote_system(name=name)
+        except storops_ex.UnityResourceNotFoundError:
+            LOG.warning("Not found remote system with name %s. Return None.",
+                        name)
+            return None
+
+    def get_replication_session(self, name=None,
+                                src_resource_id=None, dst_resource_id=None):
+        """Gets replication session via its name.
+
+        :param name: replication session name.
+        :param src_resource_id: replication session's src_resource_id.
+        :param dst_resource_id: replication session's dst_resource_id.
+        :return: replication session.
+        """
+        try:
+            return self.system.get_replication_session(
+                name=name, src_resource_id=src_resource_id,
+                dst_resource_id=dst_resource_id)
+        except storops_ex.UnityResourceNotFoundError:
+            raise ClientReplicationError(
+                'Replication session with name %(name)s not found.'.format(
+                    name=name))
+
+    def failover_replication(self, rep_session):
+        """Fails over a replication session.
+
+        :param rep_session: replication session to fail over.
+        """
+        name = rep_session.name
+        LOG.debug('Failing over replication: %s', name)
+        try:
+            # In OpenStack, only support to failover triggered from secondary
+            # backend because the primary could be down. Then `sync=False`
+            # is required here which means it won't sync from primary to
+            # secondary before failover.
+            return rep_session.failover(sync=False)
+        except storops_ex.UnityException as ex:
+            raise ClientReplicationError(
+                'Failover of replication: %(name)s failed, '
+                'error: %(err)s'.format(name=name, err=ex)
+            )
+        LOG.debug('Replication: %s failed over', name)
+
+    def failback_replication(self, rep_session):
+        """Fails back a replication session.
+
+        :param rep_session: replication session to fail back.
+        """
+        name = rep_session.name
+        LOG.debug('Failing back replication: %s', name)
+        try:
+            # If the replication was failed-over before initial copy done,
+            # following failback will fail without `force_full_copy` because
+            # the primary # and secondary data have no common base.
+            # `force_full_copy=True` has no effect if initial copy done.
+            return rep_session.failback(force_full_copy=True)
+        except storops_ex.UnityException as ex:
+            raise ClientReplicationError(
+                'Failback of replication: %(name)s failed, '
+                'error: %(err)s'.format(name=name, err=ex)
+            )
+        LOG.debug('Replication: %s failed back', name)
+
+
+class ClientReplicationError(exception.CinderException):
+    pass
diff --git a/cinder/volume/drivers/dell_emc/unity/driver.py b/cinder/volume/drivers/dell_emc/unity/driver.py
index 646e17621ac..542f504949d 100644
--- a/cinder/volume/drivers/dell_emc/unity/driver.py
+++ b/cinder/volume/drivers/dell_emc/unity/driver.py
@@ -24,6 +24,7 @@ from cinder import interface
 from cinder.volume import configuration
 from cinder.volume import driver
 from cinder.volume.drivers.dell_emc.unity import adapter
+from cinder.volume.drivers.dell_emc.unity import replication
 from cinder.volume.drivers.san.san import san_opts
 from cinder.volume import utils
 from cinder.zonemanager import utils as zm_utils
@@ -80,9 +81,10 @@ class UnityDriver(driver.ManageableVD,
         4.2.0 - Support compressed volume
         5.0.0 - Support storage assisted volume migration
         6.0.0 - Support generic group and consistent group
+        6.1.0 - Support volume replication
     """
 
-    VERSION = '06.00.00'
+    VERSION = '06.01.00'
     VENDOR = 'Dell EMC'
     # ThirdPartySystems wiki page
     CI_WIKI_NAME = "EMC_UNITY_CI"
@@ -91,20 +93,26 @@ class UnityDriver(driver.ManageableVD,
         super(UnityDriver, self).__init__(*args, **kwargs)
         self.configuration.append_config_values(UNITY_OPTS)
         self.configuration.append_config_values(san_opts)
+
+        # active_backend_id is not None if the service is failed over.
+        self.active_backend_id = kwargs.get('active_backend_id')
+        self.replication_manager = replication.ReplicationManager()
         protocol = self.configuration.storage_protocol
         if protocol.lower() == adapter.PROTOCOL_FC.lower():
             self.protocol = adapter.PROTOCOL_FC
-            self.adapter = adapter.FCAdapter(self.VERSION)
         else:
             self.protocol = adapter.PROTOCOL_ISCSI
-            self.adapter = adapter.ISCSIAdapter(self.VERSION)
 
     @staticmethod
     def get_driver_options():
         return UNITY_OPTS
 
     def do_setup(self, context):
-        self.adapter.do_setup(self, self.configuration)
+        self.replication_manager.do_setup(self)
+
+    @property
+    def adapter(self):
+        return self.replication_manager.active_adapter
 
     def check_for_setup_error(self):
         pass
@@ -316,3 +324,8 @@ class UnityDriver(driver.ManageableVD,
     def delete_group_snapshot(self, context, group_snapshot, snapshots):
         """Deletes a snapshot of consistency group."""
         return self.adapter.delete_group_snapshot(group_snapshot)
+
+    def failover_host(self, context, volumes, secondary_id=None, groups=None):
+        """Failovers volumes to secondary backend."""
+        return self.adapter.failover(volumes,
+                                     secondary_id=secondary_id, groups=groups)
diff --git a/cinder/volume/drivers/dell_emc/unity/replication.py b/cinder/volume/drivers/dell_emc/unity/replication.py
new file mode 100644
index 00000000000..68c766d9788
--- /dev/null
+++ b/cinder/volume/drivers/dell_emc/unity/replication.py
@@ -0,0 +1,214 @@
+# Copyright (c) 2016 - 2019 Dell Inc. or its subsidiaries.
+# All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+import random
+
+from oslo_log import log as logging
+from oslo_utils import excutils
+
+from cinder import exception
+from cinder.volume.drivers.dell_emc.unity import adapter as unity_adapter
+
+LOG = logging.getLogger(__name__)
+
+
+class ReplicationDevice(object):
+    def __init__(self, conf_dict, driver):
+        """Constructs a replication device from driver configuration.
+
+        :param conf_dict: the conf of one replication device entry. It's a
+            dict with content like
+            `{backend_id: vendor-id-1, key-1: val-1, ...}`
+        :param driver: the backend driver.
+        """
+        driver_conf = driver.configuration
+
+        self.backend_id = conf_dict.get('backend_id')
+        self.san_ip = conf_dict.get('san_ip', None)
+        if (self.backend_id is None or not self.backend_id.strip()
+                or self.san_ip is None or not self.san_ip.strip()):
+            LOG.error('No backend_id or san_ip in %(conf)s of '
+                      '%(group)s.replication_device',
+                      conf=conf_dict, group=driver_conf.config_group)
+            raise exception.InvalidConfigurationValue(
+                option='%s.replication_device' % driver_conf.config_group,
+                value=driver_conf.replication_device)
+
+        # Use the driver settings if not configured in replication_device.
+        self.san_login = conf_dict.get('san_login', driver_conf.san_login)
+        self.san_password = conf_dict.get('san_password',
+                                          driver_conf.san_password)
+
+        # Max time (in minute) out of sync is a setting for replication.
+        # It means maximum time to wait before syncing the source and
+        # destination. `0` means it is a sync replication. Default is `60`.
+        try:
+            self.max_time_out_of_sync = int(
+                conf_dict.get('max_time_out_of_sync', 60))
+        except ValueError:
+            LOG.error('max_time_out_of_sync is not a number, %(conf)s of '
+                      '%(group)s.replication_device',
+                      conf=conf_dict, group=driver_conf.config_group)
+            raise exception.InvalidConfigurationValue(
+                option='%s.replication_device' % driver_conf.config_group,
+                value=driver_conf.replication_device)
+        if self.max_time_out_of_sync < 0:
+            LOG.error('max_time_out_of_sync should be greater than 0, '
+                      '%(conf)s of %(group)s.replication_device',
+                      conf=conf_dict, group=driver_conf.config_group)
+            raise exception.InvalidConfigurationValue(
+                option='%s.replication_device' % driver_conf.config_group,
+                value=driver_conf.replication_device)
+
+        self.driver = driver
+        self._adapter = init_adapter(driver.get_version(), driver.protocol)
+        self._dst_pool = None
+        self._serial_number = None
+
+    @property
+    def device_conf(self):
+        conf = self.driver.configuration
+        conf.san_ip = self.san_ip
+        conf.san_login = self.san_login
+        conf.san_password = self.san_password
+        return conf
+
+    def setup_adapter(self):
+        if not self._adapter.is_setup:
+            try:
+                self._adapter.do_setup(self.driver, self.device_conf)
+            except exception.CinderException:
+                with excutils.save_and_reraise_exception():
+                    LOG.error('replication_device configured but its adapter '
+                              'setup failed: %s', self.backend_id)
+
+    @property
+    def adapter(self):
+        self.setup_adapter()
+        return self._adapter
+
+    @property
+    def destination_pool(self):
+        if self._dst_pool is None:
+            LOG.debug('getting destination pool for replication device: %s',
+                      self.backend_id)
+            pools_dict = self.adapter.storage_pools_map
+            pool_name = random.choice(list(pools_dict))
+            LOG.debug('got destination pool for replication device: %s, '
+                      'pool: %s', self.backend_id, pool_name)
+            self._dst_pool = pools_dict[pool_name]
+
+        return self._dst_pool
+
+
+def init_adapter(version, protocol):
+    if protocol == unity_adapter.PROTOCOL_FC:
+        return unity_adapter.FCAdapter(version)
+    return unity_adapter.ISCSIAdapter(version)
+
+
+DEFAULT_ADAPTER_NAME = 'default'
+
+
+class ReplicationManager(object):
+    def __init__(self):
+        self.is_replication_configured = False
+        self.default_conf = None
+        self.default_device = None
+        self.replication_devices = None
+        self.active_backend_id = None
+
+    def do_setup(self, driver):
+        self.default_conf = driver.configuration
+
+        self.replication_devices = self.parse_rep_device(driver)
+        if DEFAULT_ADAPTER_NAME in self.replication_devices:
+            LOG.error('backend_id cannot be `default`')
+            raise exception.InvalidConfigurationValue(
+                option=('%s.replication_device'
+                        % self.default_conf.config_group),
+                value=self.default_conf.replication_device)
+
+        # Only support one replication device currently.
+        if len(self.replication_devices) > 1:
+            LOG.error('At most one replication_device is supported')
+            raise exception.InvalidConfigurationValue(
+                option=('%s.replication_device'
+                        % self.default_conf.config_group),
+                value=self.default_conf.replication_device)
+
+        self.is_replication_configured = len(self.replication_devices) >= 1
+
+        self.active_backend_id = driver.active_backend_id
+        if self.active_backend_id:
+            if self.active_backend_id not in self.replication_devices:
+                LOG.error('Service starts under failed-over status, '
+                          'active_backend_id: %s is not empty, but not in '
+                          'replication_device.', self.active_backend_id)
+                raise exception.InvalidConfigurationValue(
+                    option=('%s.replication_device'
+                            % self.default_conf.config_group),
+                    value=self.default_conf.replication_device)
+        else:
+            self.active_backend_id = DEFAULT_ADAPTER_NAME
+
+        default_device_conf = {
+            'backend_id': DEFAULT_ADAPTER_NAME,
+            'san_ip': driver.configuration.san_ip
+        }
+        self.default_device = ReplicationDevice(default_device_conf, driver)
+        if not self.is_service_failed_over:
+            # If service doesn't fail over, setup the adapter.
+            # Otherwise, the primary backend could be down, adapter setup could
+            # fail.
+            self.default_device.setup_adapter()
+
+        if self.is_replication_configured:
+            # If replication_device is configured, consider the replication is
+            # enabled and check the same configuration is valid for secondary
+            # backend or not.
+            self.setup_rep_adapters()
+
+    @property
+    def is_service_failed_over(self):
+        return (self.active_backend_id is not None
+                and self.active_backend_id != DEFAULT_ADAPTER_NAME)
+
+    def setup_rep_adapters(self):
+        for backend_id, rep_device in self.replication_devices.items():
+            rep_device.setup_adapter()
+
+    @property
+    def active_adapter(self):
+        if self.is_service_failed_over:
+            return self.replication_devices[self.active_backend_id].adapter
+        else:
+            self.active_backend_id = DEFAULT_ADAPTER_NAME
+            return self.default_device.adapter
+
+    @staticmethod
+    def parse_rep_device(driver):
+        driver_conf = driver.configuration
+        rep_devices = {}
+        if not driver_conf.replication_device:
+            return rep_devices
+
+        for device_conf in driver_conf.replication_device:
+            rep_device = ReplicationDevice(device_conf, driver)
+            rep_devices[rep_device.backend_id] = rep_device
+        return rep_devices
+
+    def failover_service(self, backend_id):
+        self.active_backend_id = backend_id
diff --git a/cinder/volume/drivers/dell_emc/unity/utils.py b/cinder/volume/drivers/dell_emc/unity/utils.py
index d931924a0d1..a5f45d5c257 100644
--- a/cinder/volume/drivers/dell_emc/unity/utils.py
+++ b/cinder/volume/drivers/dell_emc/unity/utils.py
@@ -18,6 +18,8 @@ from __future__ import division
 import contextlib
 from distutils import version
 import functools
+import json
+
 from oslo_log import log as logging
 from oslo_utils import fnmatch
 from oslo_utils import units
@@ -348,3 +350,45 @@ def is_multiattach_to_host(volume_attachment, host_name):
                   if a.attach_status == fields.VolumeAttachStatus.ATTACHED and
                   a.attached_host == host_name]
     return len(attachment) > 1
+
+
+def load_replication_data(rep_data_str):
+    # rep_data_str is string dumped from a dict like:
+    # {
+    #     'default': 'rep_session_name_failed_over',
+    #     'backend_id_1': 'rep_session_name_1',
+    #     'backend_id_2': 'rep_session_name_2'
+    # }
+    return json.loads(rep_data_str)
+
+
+def dump_replication_data(model_update, rep_data):
+    # rep_data is a dict like:
+    # {
+    #     'backend_id_1': 'rep_session_name_1',
+    #     'backend_id_2': 'rep_session_name_2'
+    # }
+    model_update['replication_driver_data'] = json.dumps(rep_data)
+    return model_update
+
+
+def enable_replication_status(model_update, rep_data):
+    model_update['replication_status'] = fields.ReplicationStatus.ENABLED
+    return dump_replication_data(model_update, rep_data)
+
+
+def error_replication_status(model_update):
+    # model_update is a dict like:
+    # {
+    #     'volume_id': volume.id,
+    #     'updates': {
+    #         'provider_id': new_provider_id,
+    #         'provider_location': new_provider_location,
+    #         'replication_status': fields.ReplicationStatus.FAILOVER_ERROR,
+    #         ...
+    #     }
+    # }
+    model_update['updates']['replication_status'] = (
+        fields.ReplicationStatus.FAILOVER_ERROR
+    )
+    return model_update
diff --git a/doc/source/configuration/block-storage/drivers/dell-emc-unity-driver.rst b/doc/source/configuration/block-storage/drivers/dell-emc-unity-driver.rst
index 988ed92974d..11f8de52b7e 100644
--- a/doc/source/configuration/block-storage/drivers/dell-emc-unity-driver.rst
+++ b/doc/source/configuration/block-storage/drivers/dell-emc-unity-driver.rst
@@ -15,7 +15,7 @@ Prerequisites
 +===================+=================+
 | Unity OE          | 4.1.X or newer  |
 +-------------------+-----------------+
-| storops           | 0.5.10 or newer |
+| storops           | 1.1.0 or newer  |
 +-------------------+-----------------+
 
 
@@ -41,6 +41,7 @@ Supported operations
 - Clone a consistent group.
 - Create a consistent group from a snapshot.
 - Attach a volume to multiple servers simultaneously (multiattach).
+- Volume replications.
 
 Driver configuration
 ~~~~~~~~~~~~~~~~~~~~
@@ -411,6 +412,63 @@ snapshots, the volume type extra specs would also have the following entry:
 Refer to :doc:`/admin/blockstorage-groups`
 for command lines detail.
 
+Volume replications
+~~~~~~~~~~~~~~~~~~~
+
+To enable volume replications, follow below steps:
+
+1. On Unisphere, configure remote system and interfaces for replications.
+
+The way could be different depending on the type of replications - sync or async.
+Refer to `Unity Replication White Paper
+<https://www.emc.com/collateral/white-papers/h15088-dell-emc-unity-replication-technologies.pdf>`_
+for more detail.
+
+2. Add `replication_device` to storage backend settings in `cinder.conf`, then
+   restart Cinder Volume service.
+
+    Example of `cinder.conf` for volume replications:
+
+    .. code-block:: ini
+
+        [unity-primary]
+        san_ip = xxx.xxx.xxx.xxx
+        ...
+        replication_device = backend_id:unity-secondary,san_ip:yyy.yyy.yyy.yyy,san_password:****,max_time_out_of_sync:60
+
+    - Only one `replication_device` can be configured for each primary backend.
+    - Keys `backend_id`, `san_ip`, `san_password`, and `max_time_out_of_sync`
+      are supported in `replication_device`, while `backend_id` and `san_ip`
+      are required.
+    - `san_password` uses the same one as primary backend's if it is omitted.
+    - `max_time_out_of_sync` is the max time in minutes replications are out of
+      sync. It must be equal or greater than `0`. `0` means sync replications
+      of volumes will be created. Note that remote systems for sync replications
+      need to be created on Unity first. `60` will be used if it is omitted.
+
+#. Create a volume type with property `replication_enabled='<is> True'`.
+
+    .. code-block:: console
+
+        $ openstack volume type create --property replication_enabled='<is> True' type-replication
+
+#. Any volumes with volume type of step #3 will failover to secondary backend
+   after `failover_host` is executed.
+
+    .. code-block:: console
+
+        $ cinder failover-host --backend_id unity-secondary stein@unity-primary
+
+#. Later, they could be failed back.
+
+    .. code-block:: console
+
+        $ cinder failover-host --backend_id default stein@unity-primary
+
+.. note:: The volume can be deleted even when it is participating in a
+    replication. The replication session will be deleted from Unity before the
+    LUN is deleted.
+
 Troubleshooting
 ~~~~~~~~~~~~~~~
 
diff --git a/doc/source/reference/support-matrix.ini b/doc/source/reference/support-matrix.ini
index ac1d9218beb..06115737688 100644
--- a/doc/source/reference/support-matrix.ini
+++ b/doc/source/reference/support-matrix.ini
@@ -478,7 +478,7 @@ driver.datera=missing
 driver.dell_emc_powermax=complete
 driver.dell_emc_ps=missing
 driver.dell_emc_sc=complete
-driver.dell_emc_unity=missing
+driver.dell_emc_unity=complete
 driver.dell_emc_vmax_af=complete
 driver.dell_emc_vmax_3=complete
 driver.dell_emc_vnx=complete
diff --git a/driver-requirements.txt b/driver-requirements.txt
index e30468c60df..0100a72ba38 100644
--- a/driver-requirements.txt
+++ b/driver-requirements.txt
@@ -31,7 +31,7 @@ rados # LGPLv2.1
 rbd # LGPLv2.1
 
 # Dell EMC VNX and Unity
-storops>=0.5.10 # Apache-2.0
+storops>=1.1.0 # Apache-2.0
 
 # INFINIDAT
 infinisdk # BSD-3
diff --git a/releasenotes/notes/unity-replication-support-2ab121a5ea5a2ade.yaml b/releasenotes/notes/unity-replication-support-2ab121a5ea5a2ade.yaml
new file mode 100644
index 00000000000..03d15d302b3
--- /dev/null
+++ b/releasenotes/notes/unity-replication-support-2ab121a5ea5a2ade.yaml
@@ -0,0 +1,4 @@
+---
+features:
+  - |
+    Dell EMC Unity Driver: Added volume replication support.