At PlayFab, one of our core tenets is no downtime. This makes challenges like the recent overhaul of our AWS topology particularly interesting. When you’re a backend-as-a-service, you can’t just turn everything off for six hours. (Or six minutes.) This, then, is a postmortem of how we migrated from AWS EC2-Classic to AWS Virtual Private Cloud (VPC) without losing our data, our customers, or our minds.