Comment 3 for bug 1341420

It's possible to request multiple instances at once. They all have to be the same flavor IIRC. If you do this, the scheduler will ensure the whole request can be met. However if you make multiple requests then as you've seen, it kind of assumes all prior requests failed unless the DB has been updated to say they succeeded.

Two obvious fixes occur to me. One, sync the scheduler with the compute hosts. Generally unacceptable but might be OK in an early TripleO context. Two, make the scheduler more optimistic. Either way is going to be tricky, work on converting to use Nova objects and splitting out Gantt has basically frozen all other work on the scheduler.