Open Stack

Hi,
There is an issue with the statistics reported when a nova compute driver has shared storage attached. That is, there may be more than one compute node reporting on the shared storage. A patch has been posted - https://review.openstack.org/#/c/155184. The direction here was to add a extra parameter to the dictionary that the driver returns for the resource utilization. The DB statistics calculation would take this into account and then do calculations accordingly.
I am not really in favor of the approach for a number of reasons:

  1.  Over the last few cycles we have been making a move to trying to better define data structures and models that we use. More specifically we have been moving to object support
  2.  A change in the DB layer may break this support.
  3.  We are trying to have versioning of various blobs of data that are passed around

My thinking is that the resource tracker should be aware that the compute node has shared storage and the changes done there. I do not think that the compute node should rely on the changes being done in the DB layer - that may be on a different host and even run a different version.

I understand that this is a high or critical bug but I think that we need to discuss more on it and try have a more robust model.
Thanks
Gary
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