One of the things I stress when talking to customers is that when one is moving to cloud, it's not just the business model that changes, but the architecture mo

One of the things I stress when talking to customers is that when one is moving to cloud, it's not just the business model that changes, but the architecture model. That may sound like cold comfort on the face of it, but it's key to getting the most out of cloud and exceed the possibilities of an on-prem architecture. Rule #1 is, everything fails. The key advantage to a good cloud provider (and there are many) is not that they can deliver a guarantee against failure (as boulos stated correctly) but that they'll allow you to design for failure. The issue becomes when the architecture in the cloud resembles that which was on-premise. While there's still some advantages, they're markedly fewer, and as you said, there's nothing you can do to prioritize your fix. They key to having a good cloud deployment is effectively utilizing the features that eliminate single points of failure so that the same storage controller failure that might knock you out in your on-prem can't knock you out in the cloud, even though the repair time for the latter might be longer. That brings its own challenges, but brings huge advantages when it comes together. Disclosure: I work for AWS.