Dell PowerMax: Added exception handling after

the masking view REST call.

Added exception handling after the masking view
REST call to retry fetching the host lunid if
it is not returned by the REST call

Updated the retry count based on trial and error.
The maximum observed retries reached the 8th attempt,
so we have set it to 8 retries.

Closes-Bug: #2081742
Change-Id: I9e8e5f38c8ab8804c5e7ae4ad5e0f650768e93c3
(cherry picked from commit c05d12875f)

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

@@ -869,10 +869,10 @@ class PowerMaxRestTest(test.TestCase):
     def test_find_mv_connections_for_vol_missing_host_lun_address(self):
         with mock.patch.object(self.rest, 'get_resource',
                                return_value=self.data.maskingview_no_lun):
-            host_lun_id = self.rest.find_mv_connections_for_vol(
-                self.data.array, self.data.masking_view_name_f,
-                self.data.device_id)
-            self.assertIsNone(host_lun_id)
+            self.assertRaises(exception.VolumeBackendAPIException,
+                              self.rest.find_mv_connections_for_vol,
+                              self.data.array, self.data.masking_view_name_f,
+                              self.data.device_id)
 
     def test_find_mv_connections_for_vol_failed(self):
         # no masking view info retrieved
@@ -883,9 +883,10 @@ class PowerMaxRestTest(test.TestCase):
         # no connection info received
         with mock.patch.object(self.rest, 'get_resource',
                                return_value={'no_conn': 'no_info'}):
-            host_lun_id2 = self.rest.find_mv_connections_for_vol(
-                self.data.array, self.data.masking_view_name_f, device_id)
-            self.assertIsNone(host_lun_id2)
+            self.assertRaises(exception.VolumeBackendAPIException,
+                              self.rest.find_mv_connections_for_vol,
+                              self.data.array, self.data.masking_view_name_f,
+                              self.data.device_id)
 
     def test_get_storage_groups_from_volume(self):
         array = self.data.array

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

@@ -1621,7 +1621,7 @@ class PowerMaxRest(object):
                 self.delete_resource(array, SLOPROVISIONING,
                                      "volume", device_id)
 
-    @retry(retry_exc_tuple, interval=2, retries=3)
+    @retry(retry_exc_tuple, interval=2, retries=8)
     def find_mv_connections_for_vol(self, array, maskingview, device_id):
         """Find the host_lun_id for a volume in a masking view.
 
@@ -1644,28 +1644,42 @@ class PowerMaxRest(object):
             try:
                 masking_view_conn = connection_info.get(
                     'maskingViewConnection')
-                if masking_view_conn and isinstance(
-                        masking_view_conn, list):
+                if (masking_view_conn and isinstance(
+                        masking_view_conn, list) and
+                        len(masking_view_conn) > 0):
                     host_lun_id = masking_view_conn[0].get(
                         'host_lun_address')
                     if host_lun_id:
                         host_lun_id = int(host_lun_id, 16)
                     else:
-                        exception_message = (
-                            _('Unable to get host_lun_address for '
-                              'device %(dev)s on masking view %(mv)s. '
-                              'Retrying...')
-                            % {'dev': device_id, 'mv': maskingview})
+                        exception_message = (_("Unable to get "
+                                               "host_lun_address for device "
+                                               "%(dev)s on masking view "
+                                               "%(mv)s. Retrying...")
+                                             % {"dev": device_id,
+                                                "mv": maskingview})
                         LOG.warning(exception_message)
                         raise exception.VolumeBackendAPIException(
                             message=exception_message)
+                else:
+                    exception_message = (_("Unable to retrieve connection "
+                                           "information for volume %(vol)s "
+                                           "in masking view %(mv)s. "
+                                           "Retrying...")
+                                         % {"vol": device_id,
+                                            "mv": maskingview})
+                    LOG.warning(exception_message)
+                    raise exception.VolumeBackendAPIException(
+                        message=exception_message)
             except Exception as e:
-                exception_message = (
-                    _("Unable to retrieve connection information "
-                      "for volume %(vol)s in masking view %(mv)s. "
-                      "Exception received: %(e)s. Retrying...")
-                    % {'vol': device_id, 'mv': maskingview,
-                       'e': e})
+                exception_message = (_("Unable to retrieve connection "
+                                       "information for volume %(vol)s "
+                                       "in masking view %(mv)s. "
+                                       "Exception received: %(e)s. "
+                                       "Retrying...")
+                                     % {"vol": device_id,
+                                        "mv": maskingview,
+                                        "e": e})
                 LOG.warning(exception_message)
                 raise exception.VolumeBackendAPIException(
                     message=exception_message)

releasenotes/notes/bug-2081742-dell-powermax-rest-api-hostlunid-ee22d0105c990ea0.yaml

@@ -0,0 +1,8 @@
+---
+fixes:
+  - |
+    Dell PowerMax Driver `bug #2081742
+    <https://bugs.launchpad.net/cinder/+bug/2081742>`_: The REST
+    API calls for the masking view connection do not return
+    the HostLUN ID immediately. To address this, an exception
+    has been added to implement a retry mechanism.