Skip to content

Replication Strategies

An interactive distributed-systems replication simulator. It implements and visualizes the four canonical replication strategies side by side — with real network-fault injection — so you can see the trade-offs between consistency, availability, and latency play out live.

What it simulates

One leader accepts all writes and replicates an append-entries log to followers. Toggle between async, semi-sync, and sync durability, observe follower lag, and watch catch-up after dropped entries.

Every node accepts writes simultaneously. Concurrent writes are detected via vector clocks and reconciled by a pluggable resolver: LWW, vector-clock, CRDT (G-Counter / RGA), or manual. Anti-entropy reconciles diverged state after a partition heals.

Tunable N/W/R quorums with consistent-hash preference-list routing, sloppy quorums with hinted handoff, async/sync/digest read repair, and region-aware consistency levels (LOCAL_QUORUM / EACH_QUORUM). The W + R > N guarantee is enforced and visualized.

Real leader election, log replication with log-matching, majority commit, automatic failover on leader crash, and log compaction with snapshots. Pause a node and watch a new leader get elected in real time.

Correctness tooling

Checker Endpoint What it verifies
Linearizability GET /clusters/{id}/linearizable Porcupine-style history check
Invariants GET /clusters/{id}/invariants Always-on convergence + quorum overlap
Convergence GET /clusters/{id}/convergence All online replicas agree on every key
Merkle anti-entropy POST /clusters/{id}/anti-entropy Syncs only the divergent key-set

Interactive demos

Beyond the four strategies, the CLI and API expose primitive demos you can drive without a UI:

  • 2PC — two-phase commit with a simulated coordinator crash
  • MVCC — snapshot-isolated reads across concurrent writers
  • WAL durability — buffered / fsync / group-commit write modes
  • SWIM gossip — failure detection and membership propagation
  • Paxos / Multi-Paxos — single-decree and multi-decree consensus
  • Deterministic clock — seeded simulation clock for reproducible replays

Get started

# 1 — run the backend (default port 8080)
go run ./cmd/server

# 2 — run the frontend BFF (serves the UI on :3001)
cd frontend && bun server/bff.ts

# 3 — open the simulator
open http://localhost:3001

Or use Docker Compose:

docker compose up

See the Quick Start for full details including Docker and config options.