“In the four years that I led the team (until Spring 2021), we did not experience a single severe outage (nothing higher than a SEV3).”
A Yale professor on sabbatical built Delos, the storage layer now replacing ZooKeeper at Facebook. Three people got it to production in under a year. The best advice on the list is the boring kind: start with one customer and read their code. Most infra teams build for imaginary users and wonder why nobody migrates.