Open Stack

Several months ago I proposed an experiment [0] to see if switching the data model for the Nova scheduler to use Cassandra as the backend would be a significant improvement as opposed to the current design using multiple copies of the same data (compute_node in MySQL DB, HostState in memory in the scheduler, ResourceTracker in memory in the compute node) and trying to keep them all in sync via passing messages. It was discussed at the Nova mid-cycle, and while there was certainly not an immediate rejection, it was felt very strongly that there was too much work for us to focus on, and such an experiment, no matter how potentially beneficial, would prevent us from accomplishing the tasks we had undertaken for Liberty. And, as disappointed as I was, I had to agree. So I promised that I would write up my ideas on why I thought that such an experiment was worthwhile.

I've finally gotten around to finishing writing up that proposal [1], and I'd like to hope that it would be the basis for future discussions about addressing some of the underlying issues that exist in OpenStack for historical reasons, and how we might rethink these choices today. I'd prefer comments and discussion here on the dev list, so that all can see your ideas, but I will be in Tokyo for the summit, and would also welcome some informal discussion there, too.

-- Ed Leafe

[0] http://lists.openstack.org/pipermail/openstack-dev/2015-July/069593.html
[1] http://blog.leafe.com/reimagining_scheduler/
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