How Netflix Built a Distributed Write Ahead Log For Its Data Platform

Netflix built a distributed Write-Ahead Log (WAL) system to solve data reliability issues across their platform. The WAL captures every data change before applying it to databases, enabling automatic retries, cross-region replication, and multi-partition consistency. Built on top of their Data Gateway Infrastructure, it uses Kafka and Amazon SQS as pluggable backends, supports multiple use cases through namespaces, and scales independently through sharded deployments. The system provides durability guarantees while allowing teams to configure retry logic, delays, and targets without code changes.