> If using a distributed system with (semi-)synchronous WAL replication is not an option and losing incremental data is not acceptable, use redundant power supplies.
Also be sure to plug each redundant power supply into a separate UPS, and avoid equipment that has redundant power supplies on a single feed. UPS failures are a bear.
And also make sure no UPS is ever loaded over ~40%, so when one of the pair fails the other can handle the full load. And always set them up in isolated pairs, with no equipment plugged into a pair member and a non-member, to prevent cascading failures.
Also be sure to plug each redundant power supply into a separate UPS, and avoid equipment that has redundant power supplies on a single feed. UPS failures are a bear.