Description of problem: The resizing of an instance requires the parameter allow_resize_to_same_host in the /etc/nova/nova.conf must be set to true. Currently, the parameter is commented out as: #allow_resize_to_same_host=false Thus the resize action is not available. Version-Release number of selected component (if applicable): openstack-tripleo-image-elements-0.9.6-5.el7ost.noarch openstack-heat-templates-0-0.6.20150605git.el7ost.noarch openstack-tripleo-heat-templates-0.8.6-23.el7ost.noarch openstack-tripleo-0.0.7-0.1.1664e566.el7ost.noarch openstack-tripleo-puppet-elements-0.0.1-3.el7ost.noarch How reproducible: 100% Steps to Reproduce: 1. Launch an instance 2. Resize the instance 3. Check the configuration in the nova.conf of the compute nodes # sudo grep allow_resize_to_same_host /etc/nova/nova.conf Actual results: The resize action fails with the error: ERROR (BadRequest): No valid host was found. No valid host found for resize (HTTP 400) Expected results: The resize of the instance should succeed Additional info:
"The resizing of an instance requires the parameter allow_resize_to_same_host in the /etc/nova/nova.conf must be set to true." Note that this is only true if you have exactly one compute node. In any real deployment it is not going to be an issue.
Whenever I tried to resize an instance with no relation to the number of compute nodes I had I always had to change this parameter in order for the resize to work.
Ah, that would be because of https://bugzilla.redhat.com/show_bug.cgi?id=1221776 Resizing requires the same inter-compute ssh access as migrate.
This bug did not make the OSP 8.0 release. It is being deferred to OSP 10.
I have an "all in one" installation. The "allow_resize_to_same_host=true" option solved when scaling up instances, but if we decided scaling down, did not work.
In my experience, scaling down usually fails due to the disk size in the new flavor being smaller than the previous one. Since OpenStack can't resize the partition in the instance before changing the flavor it's not possible to scale down that way. However, scaling down to a flavor with the same size disk but less cpu and memory should work fine.
Scale up is supported. Scale down only manual.