In a lab deployment, I've got the same problem. I think it's related with ceph/cinder/glance. As result, my  only lab hypervisor has "free_disk_gb = 0" (which is an error and should get ceph volume available disk) and it cannot deploy any instance:

$ openstack hypervisor stats show
+----------------------+-------+
| Field                | Value |
+----------------------+-------+
| count                | 1     |
| current_workload     | 0     |
| disk_available_least | 0     |
| free_disk_gb         | 0     |
| free_ram_mb          | 9487  |
| local_gb             | 0     |
| local_gb_used        | 0     |
| memory_mb            | 9999  |
| memory_mb_used       | 512   |
| running_vms          | 0     |
| vcpus                | 6     |
| vcpus_used           | 0     |
+----------------------+-------+


Checking cinder_volume logs in one storage node, I get:

2017-10-23 08:49:07.768 735 INFO cinder.volume.manager [req-af1815ba-30f8-4a72-8097-756219536c65 - - - - -] Starting volume driver RBDDriver (1.2.0)
2017-10-23 08:49:07.770 735 DEBUG cinder.volume.drivers.rbd [req-af1815ba-30f8-4a72-8097-756219536c65 - - - - -] connecting to ceph (timeout=5). _do_conn /var/lib/kolla/venv/local/lib/python2.7/site-packages/cinder/volume/drivers/rbd.py:308
2017-10-23 08:49:07.794 735 DEBUG cinder.volume.drivers.rbd [req-af1815ba-30f8-4a72-8097-756219536c65 - - - - -] connecting to ceph (timeout=5). _do_conn /var/lib/kolla/venv/local/lib/python2.7/site-packages/cinder/volume/drivers/rbd.py:308
2017-10-23 08:49:07.816 735 ERROR oslo_service.service [req-af1815ba-30f8-4a72-8097-756219536c65 - - - - -] Error starting thread.: IndexError: list index out of range
2017-10-23 08:49:07.816 735 ERROR oslo_service.service Traceback (most recent call last):
2017-10-23 08:49:07.816 735 ERROR oslo_service.service   File "/var/lib/kolla/venv/local/lib/python2.7/site-packages/oslo_service/service.py", line 721, in run_service
2017-10-23 08:49:07.816 735 ERROR oslo_service.service     service.start()
2017-10-23 08:49:07.816 735 ERROR oslo_service.service   File "/var/lib/kolla/venv/local/lib/python2.7/site-packages/cinder/service.py", line 242, in start
2017-10-23 08:49:07.816 735 ERROR oslo_service.service     service_id=Service.service_id)
2017-10-23 08:49:07.816 735 ERROR oslo_service.service   File "/var/lib/kolla/venv/local/lib/python2.7/site-packages/cinder/volume/manager.py", line 440, in init_host
2017-10-23 08:49:07.816 735 ERROR oslo_service.service     self.driver.init_capabilities()
2017-10-23 08:49:07.816 735 ERROR oslo_service.service   File "/var/lib/kolla/venv/local/lib/python2.7/site-packages/cinder/volume/driver.py", line 704, in init_capabilities
2017-10-23 08:49:07.816 735 ERROR oslo_service.service     stats = self.get_volume_stats(True)
2017-10-23 08:49:07.816 735 ERROR oslo_service.service   File "/var/lib/kolla/venv/local/lib/python2.7/site-packages/cinder/volume/drivers/rbd.py", line 483, in get_volume_stats
2017-10-23 08:49:07.816 735 ERROR oslo_service.service     self._update_volume_stats()
2017-10-23 08:49:07.816 735 ERROR oslo_service.service   File "/var/lib/kolla/venv/local/lib/python2.7/site-packages/cinder/volume/drivers/rbd.py", line 466, in _update_volume_stats
2017-10-23 08:49:07.816 735 ERROR oslo_service.service     free_capacity, total_capacity = self._get_pool_stats()
2017-10-23 08:49:07.816 735 ERROR oslo_service.service   File "/var/lib/kolla/venv/local/lib/python2.7/site-packages/cinder/volume/drivers/rbd.py", line 419, in _get_pool_stats
2017-10-23 08:49:07.816 735 ERROR oslo_service.service     if pool['name'] == pool_name][0]['stats']
2017-10-23 08:49:07.816 735 ERROR oslo_service.service IndexError: list index out of range
2017-10-23 08:49:07.816 735 ERROR oslo_service.service