NoValidHost: No valid host was found. There are not enough hosts available.

2016-05-10 10:51:10.504 15485 WARNING nova.scheduler.utils [req-3e227034-ee2d-4275-a9d8-84ef17fb066f 5c50e3803049470283f7a9d18e871096 28d5644376ba4d3bab3a30e09a0b28d1 - - -] [instance: ffe48569-0392-4c11-81b9-0f66b7d74380] Setting instance to ERROR state.
2016-05-10 16:04:19.903 15485 WARNING nova.scheduler.utils [req-3acabf1d-00c1-4aee-925d-821f279c3b9e 5c50e3803049470283f7a9d18e871096 28d5644376ba4d3bab3a30e09a0b28d1 - - -] Failed to compute_task_build_instances: No valid host was found. There are not enough hosts available.
Traceback (most recent call last):

  File "/usr/lib/python2.7/dist-packages/oslo_messaging/rpc/server.py", line 142, in inner
    return func(*args, **kwargs)

  File "/usr/lib/python2.7/dist-packages/nova/scheduler/manager.py", line 84, in select_destinations
    filter_properties)

  File "/usr/lib/python2.7/dist-packages/nova/scheduler/filter_scheduler.py", line 90, in select_destinations
    raise exception.NoValidHost(reason=reason)

NoValidHost: No valid host was found. There are not enough hosts available.

2016-05-10 16:04:19.904 15485 WARNING nova.scheduler.utils [req-3acabf1d-00c1-4aee-925d-821f279c3b9e 5c50e3803049470283f7a9d18e871096 28d5644376ba4d3bab3a30e09a0b28d1 - - -] [instance: a200841b-219f-4d76-bd30-b4270f10a1d8] Setting instance to ERROR state.
2016-05-10 17:20:55.511 15485 WARNING nova.scheduler.utils [req-75d810e3-98df-4082-9a84-cd14aed49d16 5c50e3803049470283f7a9d18e871096 28d5644376ba4d3bab3a30e09a0b28d1 - - -] Failed to compute_task_build_instances: No valid host was found. There are not enough hosts available.
Traceback (most recent call last):

  File "/usr/lib/python2.7/dist-packages/oslo_messaging/rpc/server.py", line 142, in inner
    return func(*args, **kwargs)

  File "/usr/lib/python2.7/dist-packages/nova/scheduler/manager.py", line 84, in select_destinations
    filter_properties)

  File "/usr/lib/python2.7/dist-packages/nova/scheduler/filter_scheduler.py", line 90, in select_destinations
    raise exception.NoValidHost(reason=reason)

NoValidHost: No valid host was found. There are not enough hosts available.

2016-05-10 17:20:55.512 15485 WARNING nova.scheduler.utils [req-75d810e3-98df-4082-9a84-cd14aed49d16 5c50e3803049470283f7a9d18e871096 28d5644376ba4d3bab3a30e09a0b28d1 - - -] [instance: 9c2f8933-738e-4fe8-8777-cddf68135a9f] Setting instance to ERROR state.