anti-entropy pattern
Background process that constantly reconciles replicas. Compares state hashes (Merkle trees) between nodes; where they differ, exchanges the differences and converges. The slow, thorough complement to read-repair.
Background process that constantly reconciles replicas. Compares state hashes (Merkle trees) between nodes; where they differ, exchanges the differences and converges. The slow, thorough complement to read-repair.
symptoms
- replicas slowly drifting apart over time
- data only ever read from one replica goes stale forever
- silent corruption from disk failures
causes
- replication misses some updates over time
- no continuous reconciliation mechanism
fixes
- scheduled Merkle-tree comparisons between replicas
- transfer only the diffs, not full state
- combine with read-repair for hot data
you might say
- anti-entropy sweep
- Merkle compare
- background reconciliation