Comment 5 for bug 2034704

Closing this issue.

This was intermittent, and we don't see it anymore.

The root cause was that instances took a long time to power off, nova does a graceful shutdown and after a timeout it will force the instance to stop. An issue in the booted image is likely the reason the graceful shutdown took too long/failed. We don't know exactly what change, but a good guess is that some change in upstream CentOS improved the graceful shutdown behavior in out images.