8f91d6998f
Extended chaos test coverage from 14 to 19 tests and created comprehensive documentation for safe shard migrations. New Chaos Tests: - cutover_chaos_network_partition_new_node: Network partition during cutover - cutover_chaos_drain_timeout_boundary: Drain timeout boundary conditions - cutover_chaos_concurrent_migrations: Multiple simultaneous migrations - cutover_chaos_partial_shard_failure: Varying failure rates per shard - cutover_chaos_coordinator_crash_recovery: Coordinator crash and restart Documentation: - docs/chaos_testing_report.md: Test coverage, findings, recommendations - docs/migration_runbook.md: Operational procedures, rollback, troubleshooting - notes/bf-4d9a.md: Task summary and completion report Key Findings: - Delta pass provides 0-loss cutover (validated across 19 tests) - AE on + delta on: 0.000% loss (recommended) - AE off + delta on: 0.000% loss (safe but no defense-in-depth) - AE off + delta skipped: ~2% loss (blocked by coordinator) All success criteria met: ✅ Cutover boundary chaos tests pass with anti-entropy enabled ✅ Data loss windows without anti-entropy documented and bounded ✅ Release notes include clear guidance on anti-entropy during migrations Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com> |
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Miroir
Multi-node Index Replication Orchestrator, Integrated Rebalancing
Miroir is a RAID-like orchestration layer for Meilisearch. It stripes a large index across a fleet of small-RAM Meilisearch nodes with a configurable replication factor, fans out search queries across all shards, and rebalances shard assignments when nodes are added or removed — all using the Meilisearch Community Edition.
The Problem
Meilisearch loads its entire index into memory-mapped LMDB files. A large index that exceeds a single server's available RAM cannot run on that server. The Enterprise Edition's native sharding is gated behind a commercial license. Miroir solves this without it.
How It Works
Client
│
▼
Miroir Orchestrator
├── Write path: hash(doc_id) → assign to shard → write to R replicas
├── Read path: scatter query to all shards → gather → merge ranked results
└── Rebalance: on node add/remove → recompute assignments → migrate minimum shards
Meilisearch Nodes (N instances, each holding a subset of shards)
node-0 node-1 node-2 ... node-N
Replication Factor
Analogous to software RAID — configurable per deployment:
| RF | Redundancy | Node failures tolerated | Capacity |
|---|---|---|---|
| 1 | None (stripe only) | 0 | 100% of fleet |
| 2 | One replica | 1 per shard group | 50% of fleet |
| 3 | Two replicas | 2 per shard group | 33% of fleet |
Key Components
- Orchestrator — proxy that handles shard routing, scatter-gather, result merging, and topology management
- Shard router — consistent hash function (Rendezvous/HRW) mapping document IDs to node assignments; minimal reshuffling on topology change
- Rebalancer — on node add/remove, recomputes assignments and migrates only the shards that changed owners; surviving replicas serve reads during rebuild
- Result merger — normalizes and merges ranked result sets from multiple shards into a single coherent response
Status
Design phase. See docs/ for architecture detail.