It's 4:30 in the afternoon.  You are the CTO of a hot new startup and your killer mobile app went live at 6:00 AM that morning.   Users are flocking to your app, but a couple of hours ago the calls, texts, and emails started coming in. Your servers just can't keep up.  You rush to provision new servers from the Cloud provider who promised you unlimited scalability, but the messages - now angry - keep coming.