Dell PowerMax: Enhanced the retry mechanism to verify the active snapshots.

Improved the retry mechanism of ``_cleanup_device_retry``
to account for active snapshots that take longer than
expected to be removed, thereby preventing deletion errors.

Updated the retry count based on trial and error.
The maximum observed retries reached the 6th attempt,
so we have set it to 6+1=7 retries.

Closes-Bug: #2092259
Change-Id: I9a09eb8e5b6efee59688684211d893e1af055241

cinder/tests/unit/volume/drivers/dell_emc/powermax/test_powermax_common.py

@@ -4900,3 +4900,34 @@ class PowerMaxCommonTest(test.TestCase):
         self.mock_object(self.common, 'configuration', configuration)
         kwargs_returned = self.common.get_attributes_from_cinder_config()
         self.assertEqual(kwargs_expected, kwargs_returned)
+
+    @mock.patch.object(common.PowerMaxCommon, '_cleanup_device_snapvx')
+    @mock.patch.object(rest.PowerMaxRest, 'get_volume_snapshot_list',
+                       side_effect=([{'snapshotName': 'temp-clone-snapshot'}],
+                                    []))
+    @mock.patch.object(rest.PowerMaxRest, 'find_snap_vx_sessions',
+                       side_effect=[(None, None)])
+    def test_cleanup_device_retry_1(self, mock_snapvx,
+                                    mock_ss_list, mock_clean):
+        self.common._cleanup_device_retry(
+            self.data.array, self.data.device_id, self.data.extra_specs)
+        self.assertEqual(2, mock_ss_list.call_count)
+        self.assertEqual(1, mock_snapvx.call_count)
+        self.assertEqual(2, mock_clean.call_count)
+
+    @mock.patch.object(common.PowerMaxCommon, '_cleanup_device_snapvx')
+    @mock.patch.object(rest.PowerMaxRest, 'get_volume_snapshot_list',
+                       return_value=[{'snapshotName': 'temp-clone-snapshot'}])
+    @mock.patch.object(rest.PowerMaxRest, 'find_snap_vx_sessions',
+                       side_effect=[(None, None)])
+    def test_cleanup_device_retry_2(self, mock_snapvx,
+                                    mock_ss_list, mock_clean):
+        self.assertRaises(
+            exception.VolumeBackendAPIException,
+            self.common._cleanup_device_retry,
+            self.data.array,
+            self.data.device_id,
+            self.data.extra_specs)
+        self.assertEqual(7, mock_ss_list.call_count)
+        self.assertEqual(0, mock_snapvx.call_count)
+        self.assertEqual(7, mock_clean.call_count)

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

@@ -2106,7 +2106,7 @@ class PowerMaxCommon(object):
             array, device_id, volume_name, extra_specs)
         return volume_name
 
-    @retry(retry_exc_tuple, interval=1, retries=3)
+    @retry(retry_exc_tuple, interval=2, retries=7)
     def _cleanup_device_retry(self, array, device_id, extra_specs):
         """Cleanup snapvx on the device
 

releasenotes/notes/bug-2092259-dell-powermax-volume-delete-failed-fix-active-snapshot-ccc3f9b6251d2634.yaml

@@ -0,0 +1,12 @@
+---
+fixes:
+  - |
+    Dell PowerMax Driver `bug #2092259
+    <https://bugs.launchpad.net/cinder/+bug/2092259>`_: Before
+    a volume can be deleted, the driver issues a command to clean up
+    active snapshots in the backend and then polls the backend
+    to make sure the cleanup has occurred.
+    This fix enhances the polling mechanism to give the backend
+    more time to do the cleanup, thereby increasing the probability
+    that the driver will be able to make a successful volume deletion
+    request.