VMAX driver - performance improvements in retype

This patch improves the storage assisted retype functionality by
using the Unisphere "move" API where possible, instead of removing
the volume from one storage group and then adding it to another.
This patch also corrects a minor mistake in how validity for
storage assisted retype is assessed, and explicitly blocks storage
assisted retype when a volume is attached.

Change-Id: I2270a78214457108d5baa02dac8a6cfd76e91239
Closes-Bug: #1704377

cinder/tests/unit/volume/drivers/dell_emc/vmax/test_vmax.py

@@ -170,6 +170,12 @@ class VMAXCommonData(object):
         volume_type=test_volume_type, host=fake_host,
         replication_driver_data=six.text_type(provider_location3))
 
+    test_attached_volume = fake_volume.fake_volume_obj(
+        context=ctx, name='vol1', size=2, provider_auth=None,
+        provider_location=six.text_type(provider_location), host=fake_host,
+        volume_type=test_volume_type, attach_status="attached",
+        replication_driver_data=six.text_type(provider_location3))
+
     test_legacy_vol = fake_volume.fake_volume_obj(
         context=ctx, name='vol1', size=2, provider_auth=None,
         provider_location=six.text_type(legacy_provider_location),
@@ -3905,6 +3911,10 @@ class VMAXCommonTest(test.TestCase):
                 self.common, '_find_device_on_array', return_value=None):
             self.common.retype(volume, new_type, host)
             mock_migrate.assert_not_called()
+        mock_migrate.reset_mock()
+        volume2 = self.data.test_attached_volume
+        self.common.retype(volume2, new_type, host)
+        mock_migrate.assert_not_called()
 
     def test_slo_workload_migration_valid(self):
         device_id = self.data.device_id
@@ -3978,8 +3988,13 @@ class VMAXCommonTest(test.TestCase):
                 self.data.array, device_id, self.data.srp, self.data.slo,
                 self.data.workload, volume_name, new_type, extra_specs)
             self.assertTrue(migrate_status)
+            target_extra_specs = {
+                'array': self.data.array, 'interval': 3,
+                'retries': 120, 'slo': self.data.slo,
+                'srp': self.data.srp, 'workload': self.data.workload}
             mock_remove.assert_called_once_with(
-                self.data.array, device_id, None, extra_specs, False)
+                self.data.array, device_id, volume_name,
+                target_extra_specs, reset=True)
             mock_remove.reset_mock()
             with mock.patch.object(
                     self.rest, 'get_storage_groups_from_volume',

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

@@ -1893,6 +1893,18 @@ class VMAXCommon(object):
                       {'name': volume_name})
             return False
 
+        # If the volume is attached, we can't support retype.
+        # Need to explicitly check this after the code change,
+        # as 'move' functionality will cause the volume to appear
+        # as successfully retyped, but will remove it from the masking view.
+        if volume.attach_status == 'attached':
+            LOG.error(
+                "Volume %(name)s is not suitable for storage "
+                "assisted migration using retype "
+                "as it is attached.",
+                {'name': volume_name})
+            return False
+
         if self.utils.is_replication_enabled(extra_specs):
             LOG.error("Volume %(name)s is replicated - "
                       "Replicated volumes are not eligible for "
@@ -1965,17 +1977,13 @@ class VMAXCommon(object):
         :param extra_specs: the extra specifications
         :returns: bool
         """
-        storagegroups = self.rest.get_storage_groups_from_volume(
-            array, device_id)
-        if not storagegroups:
-            LOG.warning("Volume : %(volume_name)s does not currently "
-                        "belong to any storage groups.",
-                        {'volume_name': volume_name})
-        else:
-            self.masking.remove_and_reset_members(
-                array, device_id, None, extra_specs, False)
-
         target_extra_specs = new_type['extra_specs']
+        target_extra_specs[utils.SRP] = srp
+        target_extra_specs[utils.ARRAY] = array
+        target_extra_specs[utils.SLO] = target_slo
+        target_extra_specs[utils.WORKLOAD] = target_workload
+        target_extra_specs[utils.INTERVAL] = extra_specs[utils.INTERVAL]
+        target_extra_specs[utils.RETRIES] = extra_specs[utils.RETRIES]
         is_compression_disabled = self.utils.is_compression_disabled(
             target_extra_specs)
 
@@ -1988,8 +1996,19 @@ class VMAXCommon(object):
                       "Exception received was %(e)s.", {'e': e})
             return False
 
+        storagegroups = self.rest.get_storage_groups_from_volume(
+            array, device_id)
+        if not storagegroups:
+            LOG.warning("Volume : %(volume_name)s does not currently "
+                        "belong to any storage groups.",
+                        {'volume_name': volume_name})
             self.masking.add_volume_to_storage_group(
                 array, device_id, target_sg_name, volume_name, extra_specs)
+        else:
+            self.masking.remove_and_reset_members(
+                array, device_id, volume_name, target_extra_specs,
+                reset=True)
+
         # Check that it has been added.
         vol_check = self.rest.is_volume_in_storagegroup(
             array, device_id, target_sg_name)
@@ -2068,7 +2087,7 @@ class VMAXCommon(object):
                 target_combination = ("%(targetSlo)s+%(targetWorkload)s"
                                       % {'targetSlo': target_slo,
                                          'targetWorkload': target_workload})
-                if target_combination in emc_fast_setting:
+                if target_combination == emc_fast_setting:
                     # Check if migration is from compression to non compression
                     # or vice versa
                     if not do_change_compression: