Instance can't be resized to a different flavor when all hypervisor CPUs are used.

[Olga Klochkova]

Hypervisor has enough memory to perform resize
When active instance is being resized to a different flavor having the same amount of CPUs but different amount of RAM, operation fails with error message: "Error: No valid host was found. No valid host found for resize (HTTP 400) (Request-ID: req-0837fc41-e214-4bf1-bda3-1371063000bf) "

Expected result: since amount of used CPUs should not increase as a result of the resize, operation should succeed.

VERSION:
  feature_groups:
    - mirantis
  production: "docker"
  release: "8.0"
  api: "1.0"
  build_number: "569"
  build_id: "569"
  fuel-nailgun_sha: "558ca91a854cf29e395940c232911ffb851899c1"
  python-fuelclient_sha: "4f234669cfe88a9406f4e438b1e1f74f1ef484a5"
  fuel-agent_sha: "658be72c4b42d3e1436b86ac4567ab914bfb451b"
  fuel-nailgun-agent_sha: "b2bb466fd5bd92da614cdbd819d6999c510ebfb1"
  astute_sha: "b81577a5b7857c4be8748492bae1dec2fa89b446"
  fuel-library_sha: "33634ec27be77ecfb0b56b7e07497ad86d1fdcd3"
  fuel-ostf_sha: "3bc76a63a9e7d195ff34eadc29552f4235fa6c52"
  fuel-mirror_sha: "fb45b80d7bee5899d931f926e5c9512e2b442749"
  fuelmenu_sha: "78ffc73065a9674b707c081d128cb7eea611474f"
  shotgun_sha: "63645dea384a37dde5c01d4f8905566978e5d906"
  network-checker_sha: "a43cf96cd9532f10794dce736350bf5bed350e9d"
  fuel-upgrade_sha: "616a7490ec7199f69759e97e42f9b97dfc87e85b"
  fuelmain_sha: "d605bcbabf315382d56d0ce8143458be67c53434"

[Roman Podoliaka (rpodolyaka)]

Olga, could you please provide nova-scheduler logs?

Overall, I think the behaviour you are seeing is valid in the sense, that resize effectively creates a new VM, thus, it has to check if there are enough resources for that at the time when the check is actually performed, i.e. before the original VM is deleted.

So, IMO, this should probably become Invalid.

[Olga Klochkova (oklochkova)]

If nova creates additional VM during resize then the behavior is explained by that fact.
That kind of makes sense, but is a bit confusing.

[Timur Nurlygayanov (tnurlygayanov)]

Roman, it looks like we had enough resources on the lab.

Olga, could you please attach the diagnostic snapshot to the description of the bug and move it to Confirmed state?

Thank you!

[Roman Podoliaka (rpodolyaka)]

Timur, please see my comment: the point is that you have to have *additional resources* for a successful re-size, i.e. resources reserved for the VM in question are considered to be used in this case.

[Timur Nurlygayanov (tnurlygayanov)]

So, does it mean that correct status for the issue is Invalid then?