Building a Next-Generation Key-Value Store at Airbnb

Airbnb completely rearchitected their key-value store Mussel from v1 to v2, migrating from a custom storage backend to a NewSQL system. The new architecture addresses operational complexity, capacity issues, and consistency limitations while maintaining sub-25ms p99 read latency. The migration involved a blue-green strategy with dual writes, custom pipelines, and zero-downtime transfer of over a petabyte of data across thousands of tables. Mussel v2 now combines bulk ingestion capabilities with real-time streaming and provides better cost visibility through Kubernetes-native operations.