Distributed Systems Series — Part 4.3: Fault Tolerance & High Availability Redundancy Is the Foundation, Not the Solution Post 4.1 established the taxonomy of failures — crash-stop, crash-recovery, omission, timing, gray, Byzantine, and correlated. Post 4.2 established the distinction between fault tolerance (correctness under failure) and high availability (uptime). This post addresses the structural mechanism … Read more
How quorums work in distributed systems — the W + R > N rule explained with worked examples, strict vs sloppy quorums, read repair and practical configuration guidance for Cassandra, DynamoDB and Riak.
Leader-based, multi-leader, and leaderless replication explained — with synchronous vs asynchronous replication, replication lag, quorum configuration, and real production examples from PostgreSQL, Kafka, Cassandra, and Google Spanner.
Coordination allows distributed systems to serialize access, elect leaders, and maintain correctness despite failures and unreliable time.