Open Stack

Hi,

I'm having an issue with no valid host errors when starting instances 
and I'm struggling to figure out why.  I thought the problem was disk 
space, but I changed the disk_allocation_ratio and I'm still getting no 
valid host.  The host does have plenty of disk space free, so that 
shouldn't be a problem.

However, I'm not even sure it's disk that's causing the failures because 
I can't find any information in the logs about why the no valid host is 
happening.  All I get from the scheduler is:

"Got no allocation candidates from the Placement API. This may be a 
temporary occurrence as compute nodes start up and begin reporting 
inventory to the Placement service."

While in placement I see:

2018-08-01 15:02:22.062 20 DEBUG nova.api.openstack.placement.requestlog 
[req-0a830ce9-e2af-413a-86cb-b47ae129b676 
fc44fe5cefef43f4b921b9123c95e694 b07e6dc2e6284b00ac7070aa3457c15e - 
default default] Starting request: 10.2.2.201 "GET 
/placement/allocation_candidates?limit=1000&resources=DISK_GB%3A20%2CMEMORY_MB%3A2048%2CVCPU%3A1" 
__call__ 
/usr/lib/python2.7/site-packages/nova/api/openstack/placement/requestlog.py:38
2018-08-01 15:02:22.103 20 INFO nova.api.openstack.placement.requestlog 
[req-0a830ce9-e2af-413a-86cb-b47ae129b676 
fc44fe5cefef43f4b921b9123c95e694 b07e6dc2e6284b00ac7070aa3457c15e - 
default default] 10.2.2.201 "GET 
/placement/allocation_candidates?limit=1000&resources=DISK_GB%3A20%2CMEMORY_MB%3A2048%2CVCPU%3A1" 
status: 200 len: 53 microversion: 1.25

Basically it just seems to be logging that it got a request, but there's 
no information about what it did with that request.

So where do I go from here?  Is there somewhere else I can look to see 
why placement returned no candidates?

Thanks.

-Ben