Single Region RS
3 Nodes
Simple 3-node replica set in Region 1. ~1ms latency. Region failure = cluster down.
🔵 Region 1: 3 nodes
Two Region RS
3 Nodes
3-node replica set (2+1) across Region 1/2. ~10ms cross-region latency.
🔵 Region 1: 2 nodes
🟢 Region 2: 1 node
Three Region RS
5 Nodes
5-node replica set (2-2-1). Region 3 = P:0 (DR). Survives any single region failure!
🔵 Region 1: 2 nodes
🟢 Region 2: 2 nodes
🟠 Region 3: 1 P:0
⚠️ HA Misconception
4 Nodes
Common pitfall: 2+1+read-only (p:0, v:0). If Region 1 fails, no majority! Needs manual promotion.
🔵 Region 1: 2 nodes
🟢 Region 2: 1 node + 1 read-only
Single Region Configuration
All 3 nodes in Virginia (~1ms latency). If the region fails, the entire cluster goes down. Majority required: 2 nodes.
👆 Tip: Click on any node to simulate failure/recovery
⚡ Operations
🇺🇸 Region Failure
📝 Write Concern
w:1
w:majority
w:all
📚 Read Preference
🎮 Cluster
🎬 Demo
0
Writes
0
Reads
0
Failed
0
Elections
0ms
Avg Latency
🔗 Connection String
mongodb+srv://<username>:<password>@rs0-single.mongodb.net/?retryWrites=true&w=majority&readPreference=secondaryPreferred
🔀 Query Routers (mongos)
⚙️ Config Servers (CSRS)
📋 Event Log