Openstack Train "No valid host was found." troubleshooting

 

<Symptom>

1. You get the error message "Failed to schedule instances: NoValidHost_Remote: No valid host was found." in /var/log/nova/nova-conductor.log, when you are installing an instance with image and flavor.

2. If you use Heat orchestration for installation, you get the error message "heat.engine.resource ResourceInError: Went to status ERROR due to "Message: No valid host was found. , Code: 500"" in /var/log/heat/heat-engine.log

 

<Root Cause>

1. Resource shortage.

if your set flavor requests more resources that Openstack can use for vCPU, RAM, Disk, these messages will be raised.

if your image requests more resources than what Flavor sets, these messages will be raised.

 

<Action>

1. Please check the flavor set and Openstack resources.

2. Please make sure that the flavor set meets the minimum resource which your image requests.

 

In my case, my compute node has 2 vCPU but I tried to create an instance for 4 vCPU.

maybe my OpenStack does not support 'overcommit' to use more CPUs than what I have.

 

 

 

<Related log>

ERROR nova.conductor.manager ~~~~ Failed to schedule instances: NoValidHost_Remote: No valid host was found.

ERROR heat.engine.resource ~~~~~ ResourceInError: Went to status ERROR due to "Message: No valid host was found., Code: 500"

ERROR oslo_messaging.rpc.server ~~~~~is unacceptable: Image virtual size is 65GB and doesn't fit in a volume of size 20GB.