I have setup a multi nodes Openstack env using tripleO for a PoC. The environment consists of (Running on baremetal):

1- Undercloud
2- Overcloud:
        -Controller
        -Compute-0
        -Compute-1

I have created a few instances and everything is fine but now I'm not able to create any new instance. I have checked the compute resources and they are plenty. I'm using cinder for both storing the instances and images.

 (overcloud) [heat-admin@overcloud-controller-0 ~]$ openstack compute service list
+----+------------------+---------------------------------+-----------+---------+-------+----------------------------+
| ID | Binary           | Host                            | Zone      | Status  | State | Updated At                 |
+----+------------------+---------------------------------+-----------+---------+-------+----------------------------+
|  4 | nova-conductor   | overcloud-controller-0.lab.poc  | internal  | enabled | up    | 2018-03-13T08:50:50.000000 |
| 18 | nova-compute     | overcloud-novacompute-1.lab.poc | compute-1 | enabled | up    | 2018-03-13T08:50:49.000000 |
| 19 | nova-consoleauth | overcloud-controller-0.lab.poc  | internal  | enabled | up    | 2018-03-13T08:50:47.000000 |
| 20 | nova-scheduler   | overcloud-controller-0.lab.poc  | internal  | enabled | up    | 2018-03-13T08:50:51.000000 |
| 21 | nova-compute     | overcloud-novacompute-0.lab.poc | compute-0 | enabled | up    | 2018-03-13T08:50:50.000000 |
+----+------------------+---------------------------------+-----------+---------+-------+----------------------------+

 2018-03-13 07:13:52.676 3840 ERROR nova.conductor.manager [req-c982618d-c1c0-46f1-9182-3e542f5af8af 5c1e3b2d8bc44ca08d3ccfe9c2a6ff17 7e66bf9554f748018600d046f22acc16 - default default] Failed to schedule instances: NoValidHost_Remote: No valid host was found. There are not enough hosts available. There are not enough hosts available.
Traceback (most recent call last):

  File "/usr/lib/python2.7/site-packages/oslo_messaging/rpc/server.py", line 232, in inner
    return func(*args, **kwargs)

  File "/usr/lib/python2.7/site-packages/nova/scheduler/manager.py", line 149, in select_destinations
    alloc_reqs_by_rp_uuid, provider_summaries)

  File "/usr/lib/python2.7/site-packages/nova/scheduler/filter_scheduler.py", line 110, in select_destinations
    raise exception.NoValidHost(reason=reason)

NoValidHost: No valid host was found. There are not enough hosts available.
2018-03-13 07:13:52.676 3840 ERROR nova.conductor.manager Traceback (most recent call last):
2018-03-13 07:13:52.676 3840 ERROR nova.conductor.manager   File "/usr/lib/python2.7/site-packages/nova/conductor/manager.py", line 1036, in schedule_and_build_instances
2018-03-13 07:13:52.676 3840 ERROR nova.conductor.manager     instance_uuids)
2018-03-13 07:13:52.676 3840 ERROR nova.conductor.manager   File "/usr/lib/python2.7/site-packages/nova/conductor/manager.py", line 626, in _schedule_instances
2018-03-13 07:13:52.676 3840 ERROR nova.conductor.manager     request_spec, instance_uuids)
2018-03-13 07:13:52.676 3840 ERROR nova.conductor.manager   File "/usr/lib/python2.7/site-packages/nova/scheduler/utils.py", line 586, in wrapped
2018-03-13 07:13:52.676 3840 ERROR nova.conductor.manager     return func(*args, **kwargs)
2018-03-13 07:13:52.676 3840 ERROR nova.conductor.manager   File "/usr/lib/python2.7/site-packages/nova/scheduler/client/__init__.py", line 52, in select_destinations
2018-03-13 07:13:52.676 3840 ERROR nova.conductor.manager     instance_uuids)
2018-03-13 07:13:52.676 3840 ERROR nova.conductor.manager   File "/usr/lib/python2.7/site-packages/nova/scheduler/client/__init__.py", line 37, in __run_method
2018-03-13 07:13:52.676 3840 ERROR nova.conductor.manager     return getattr(self.instance, __name)(*args, **kwargs)
2018-03-13 07:13:52.676 3840 ERROR nova.conductor.manager   File "/usr/lib/python2.7/site-packages/nova/scheduler/client/query.py", line 33, in select_destinations
2018-03-13 07:13:52.676 3840 ERROR nova.conductor.manager     instance_uuids)
2018-03-13 07:13:52.676 3840 ERROR ...