The issue with Reddit was that they designed their application for a single, on-premise data centre, with multiple layers of redundancy at the infrastructure la

The issue with Reddit was that they designed their application for a single, on-premise data centre, with multiple layers of redundancy at the infrastructure layer. They didn't design for failure. If you design your application such that single-availability-zone EBS must be as reliable as a hardened triple mirror EMC SAN, you're going to be disappointed. If you treat EBS as what it is - commodity virtualized disk storage with moderate performance - you'll be fine. In other words, ensure you have replication of data across availability zones.