Meta's Delta storage service achieves strong consistency with chain replication

Delta: Highly available, strongly consistent storage using chain replication (2022)

Meta built Delta, an object storage service for critical build and distribution artifacts, using chain replication. It offers put, get, delete, and list operations, prioritizing simplicity and reliability over latency and storage efficiency. Writes go to the chain head and are acknowledged only after all replicas persist; reads go to the tail, ensuring strong consistency. Delta tolerates n-2 failures per chain and uses apportioned queries to let all nodes serve reads, reducing tail hotspots.