Description of problem:
We think it might be because each controller is overwriting the other controller's change.

We have a support exception for this setup with the customer.

Version-Release number of selected component (if applicable):
openstack-gnocchi-api-3.0.2-1

How reproducible:
All the time

Steps to Reproduce:
1. [storage]/driver = file on all 3 controllers
2. /var/lib/gnocchi points to same NFS share for all 3 controllers
3. wait

Actual results:
Missing metrics:

openstack metric measures show --resource-id 9f99c0c7-3d57-5152-9103-b77efa369f72 network.incoming.bytes
+---------------------------+-------------+-------------------+
| timestamp                 | granularity |             value |
+---------------------------+-------------+-------------------+
| 2017-12-11T12:10:00+00:00 |       600.0 |  2.2411082012e+11 |
| 2017-12-11T13:30:00+00:00 |       600.0 | 2.24230537049e+11 |
| 2017-12-11T13:50:00+00:00 |       600.0 |  2.2426044028e+11 |
| 2017-12-11T14:00:00+00:00 |       600.0 |  2.2427551653e+11 |
| 2017-12-11T14:30:00+00:00 |       600.0 |  2.2432091579e+11 |
| 2017-12-11T15:40:00+00:00 |       600.0 | 2.24426324382e+11 |
+---------------------------+-------------+-------------------+

Expected results:
Have metrics on every 10 minutes

Additional info:
When we turn off ceilometer on 2/3 controllers, we get 100% of the metrics