PACELC, Paxos, and Raft: How “Consistency vs Latency” Shows Up in Real Systems
Distributed systems design is mostly about choosing which pain you’re willing to live with—because you can’t eliminate it. The PACELC theorem is a practical lens for those choices, and Paxos and Raft are two of the most important tools engineers use when they decide “we’re going to pay latency to buy correctness.” This post ties them together: PACELC tells you what trade-off you’re making Paxos/Raft are two ways to implement the “consistent” side of that trade-off You’ll see concrete examples, message flows, and how partitions change behavior Why CAP isn’t enough, and why PACELC exists You likely know the CAP -style story: P artition happens → you must choose C onsistency or A vailability. The missing piece is: most of the time you’re not partitioned —you’re just dealing with latency, replication delay, tail latencies, and node slowness. PACELC adds the everyday reality: If there is a Partition (P) : you choose Availability (A) or Consistency (C) Else (E) (normal operation, n...