iDRAC RAID10 creation with greater than 16 drives

This patch enables creation of large RAID10's with greater than 16
drives when using the iDRAC hardware type.  Best practice is to not
pass span length and span depth when creating a RAID10.  In this
case, the iDRAC will calculate these values using information queried
from the RAID controller.

See this white paper on intelligent mirroring for more information:
https://www.dell.com/support/article/us/en/04/sln111362/
intelligent-mirroring-and-enhanced-raid-10-aka-raid-10e-?lang=en

Change-Id: If1fb29f8a078fdb0cb0338c86e32158093cad22e
Task: # 22634
Story: #2002771

ironic/drivers/modules/drac/raid.py

@@ -497,8 +497,14 @@ def _calculate_volume_props(logical_disk, physical_disks, free_space_mb):
 
     disks_per_span = len(selected_disks) / spans_count
 
-    logical_disk['span_depth'] = spans_count
-    logical_disk['span_length'] = disks_per_span
+    # Best practice is to not pass span_length and span_depth when creating a
+    # RAID10.  The iDRAC will dynamically calculate these values using maximum
+    # values obtained from the RAID controller.
+    logical_disk['span_depth'] = None
+    logical_disk['span_length'] = None
+    if logical_disk['raid_level'] != '1+0':
+        logical_disk['span_depth'] = spans_count
+        logical_disk['span_length'] = disks_per_span
 
     max_volume_size_mb = _max_volume_size_mb(
         logical_disk['raid_level'], selected_disks, free_space_mb,

ironic/tests/unit/drivers/modules/drac/test_raid.py

@@ -661,6 +661,57 @@ class DracRaidInterfaceTestCase(test_utils.BaseDracTest):
         mock_client = mock.Mock()
         mock_get_drac_client.return_value = mock_client
 
+        self.root_logical_disk = {
+            'size_gb': 100,
+            'raid_level': '5+0',
+            'is_root_volume': True
+        }
+        self.logical_disks = [self.root_logical_disk]
+        self.target_raid_configuration = {'logical_disks': self.logical_disks}
+        self.node.target_raid_config = self.target_raid_configuration
+        self.node.save()
+
+        physical_disks = self._generate_physical_disks()
+        mock_list_physical_disks.return_value = physical_disks
+
+        mock_commit_config.return_value = '42'
+
+        with task_manager.acquire(self.context, self.node.uuid,
+                                  shared=False) as task:
+            task.driver.raid.create_configuration(
+                task, create_root_volume=True, create_nonroot_volumes=True)
+
+            mock_client.create_virtual_disk.assert_called_once_with(
+                'RAID.Integrated.1-1',
+                ['Disk.Bay.0:Enclosure.Internal.0-1:RAID.Integrated.1-1',
+                 'Disk.Bay.1:Enclosure.Internal.0-1:RAID.Integrated.1-1',
+                 'Disk.Bay.2:Enclosure.Internal.0-1:RAID.Integrated.1-1',
+                 'Disk.Bay.3:Enclosure.Internal.0-1:RAID.Integrated.1-1',
+                 'Disk.Bay.4:Enclosure.Internal.0-1:RAID.Integrated.1-1',
+                 'Disk.Bay.5:Enclosure.Internal.0-1:RAID.Integrated.1-1'],
+                '5+0', 102400, None, 3, 2)
+
+            # Commits to the controller
+            mock_commit_config.assert_called_once_with(
+                mock.ANY, raid_controller='RAID.Integrated.1-1', reboot=True)
+
+        self.node.refresh()
+        self.assertEqual(['42'],
+                         self.node.driver_internal_info['raid_config_job_ids'])
+
+    @mock.patch.object(drac_common, 'get_drac_client', spec_set=True,
+                       autospec=True)
+    @mock.patch.object(drac_raid, 'list_physical_disks', autospec=True)
+    @mock.patch.object(drac_job, 'validate_job_queue', spec_set=True,
+                       autospec=True)
+    @mock.patch.object(drac_raid, 'commit_config', spec_set=True,
+                       autospec=True)
+    def test_create_configuration_with_nested_raid_10(
+            self, mock_commit_config, mock_validate_job_queue,
+            mock_list_physical_disks, mock_get_drac_client):
+        mock_client = mock.Mock()
+        mock_get_drac_client.return_value = mock_client
+
         self.root_logical_disk = {
             'size_gb': 100,
             'raid_level': '1+0',
@@ -687,7 +738,7 @@ class DracRaidInterfaceTestCase(test_utils.BaseDracTest):
                  'Disk.Bay.1:Enclosure.Internal.0-1:RAID.Integrated.1-1',
                  'Disk.Bay.2:Enclosure.Internal.0-1:RAID.Integrated.1-1',
                  'Disk.Bay.3:Enclosure.Internal.0-1:RAID.Integrated.1-1'],
-                '1+0', 102400, None, 2, 2)
+                '1+0', 102400, None, None, None)
 
             # Commits to the controller
             mock_commit_config.assert_called_once_with(

releasenotes/notes/drac-fix-raid10-greater-than-16-drives-a4cb107e34371a51.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    Fixes an issue where RAID 10 creation fails with greater than 16 drives
+    when using the ``idrac`` hardware type.  See bug `2002771
+    <https://storyboard.openstack.org/#!/story/2002771>`_ for details.