Nova counts disk space used in ceph as local used

[Alexander Vlasov]

 cat /etc/fuel/version.yaml
VERSION:
  feature_groups:
    - mirantis
    - experimental
  production: "docker"
  release: "6.0"
  api: "1.0"
  build_number: "58"
  build_id: "2014-12-26_14-25-46"
  astute_sha: "16b252d93be6aaa73030b8100cf8c5ca6a970a91"
  fuellib_sha: "fde8ba5e11a1acaf819d402c645c731af450aff0"
  ostf_sha: "a9afb68710d809570460c29d6c3293219d3624d4"
  nailgun_sha: "5f91157daa6798ff522ca9f6d34e7e135f150a90"
  fuelmain_sha: "81d38d6f2903b5a8b4bee79ca45a54b76c1361b8"

We have following configuration:
- MOS6.0 HA
- ceph used as rbd storage for glance and cinder
- compute local storage used as an ephemeral

have following problems:
1) when instance created with volume in cinder(ceph) we can see that hypervisor stats shows that local storage used, although it isn't true.
2) while creating instance via murano or sahara type of storage specified in flavor is not taken into account and create as ephemeral on compute.

[Roman Podoliaka (rpodolyaka)]

Could you please add info on flavors you use and how exactly you create instances?

[Alexander Vlasov (avlasov)]

I think we can drop out second problem as it is rather not a bug but a question "is it ok that while creating instances in scope of murano or sahara cluster, we can't use boot from volume"

But 1st is still relevant. For example: We have one compute node, we created one instance with ephemeral volume 1GB.
Hypervisor stats shows 1GB used in local storage. Then we are creating one instance with "boot from volume" option and volume 10GB in size. Hypervisor stats will show 11GB used in local storage.

As a result we can't create more instances than hypervisors local storage can provide disk space for, although we have enough space in ceph.

Just in case: ceph is NOT used as an ephemeral storage.
As for flavors, we were using default flavors.

[Sergey Nikitin (snikitin)]

Here we have a problem with flavors. If you use "boot from volume" or "boot from image(create new volume)" and disc size in your flavor != 0, nova will reserve this space, but it will be unused space.
Workaround:
You just need to use flavor with Root Disk size = 0 when you boot your instance ("boot from volume" or "boot from image(create new volume)")