We are seeing race condition in the Nova resource tracker when reaching
maximum compute capacity. Our hypothesis is that some instances are getting
scheduled to an hypervisor which doesn't have enough free resources
according to the resource tracker, rejecting the instance creation.
We suggest reducing the max servers to avoid hitting this race condition and
reducing the number of capacity alerts sent to our operation team.
Change-Id: Iff197a94ad988fb070efaeb6bb393bfaba6e01fb
ada328c180