Issue

• According to the news, it seems cinder block storage thin pool oversubscription is supported.

• But for EMC VNX and VMAX storage storage backend, if we try to create a thin LUN in a pool that will exceed the underlying thin pool size, it will fail.

• cinder scheduler.log will report:

2015-09-15 22:18:59.869 28219 WARNING cinder.scheduler.filters.capacity_filter [req-0253e08b-0e8f-449b-b2c4-35fd20bc1080 e325ba409fd9483da6dcfcf7ac63def8 9071a9aa0ed24eb3822acca4d483ecf3 - - -] Insufficient free space for volume creation on host overcloud-controller-0.localdomain@vnx133#openstack_pool (requested / avail): 300/226.461
...
2015-09-15 22:18:59.873 28219 WARNING cinder.scheduler.filter_scheduler [req-0253e08b-0e8f-449b-b2c4-35fd20bc1080 e325ba409fd9483da6dcfcf7ac63def8 9071a9aa0ed24eb3822acca4d483ecf3 - - -] No weighed hosts found for volume with properties: {u'name': u'vnx133_iscsi', u'qos_specs_id': None, u'deleted': False, u'created_at': u'2015-08-19T07:00:44.000000', u'updated_at': None, u'extra_specs': {u'volume_backend_name': u'vnx133'}, u'is_public': True, u'deleted_at': None, u'id': u'3e244905-0834-49d8-a14f-bae627954ef0', u'description': None}
2015-09-15 22:18:59.875 28219 ERROR cinder.scheduler.flows.create_volume [req-0253e08b-0e8f-449b-b2c4-35fd20bc1080 e325ba409fd9483da6dcfcf7ac63def8 9071a9aa0ed24eb3822acca4d483ecf3 - - -] Failed to run task cinder.scheduler.flows.create_volume.ScheduleCreateVolumeTask;volume:create: No valid host was found. No weighed hosts available