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+# Q4 - Scalability & Load Balancing
+
+## 1. Architecture
+
+See `architecture.png`.
+
+---
+
+## 2. Container Calculation
+
+### Given
+
+- Required traffic = **15,000 requests/second**
+- One container capacity = **500 requests/second**
+- Safety margin = **30%**
+
+### Effective Capacity
+
+Effective capacity per container:
+
+500 × 70% = **350 requests/second**
+
+### Required Containers
+
+15000 ÷ 350 = **42.86**
+
+Rounded up:
+
+**43 Containers**
+
+---
+
+## 3. Cold Start Strategy
+
+To reduce startup latency:
+
+- Keep 2–3 warm containers running.
+- Enable Auto Scaling when CPU > 70%.
+- Pre-pull Docker images on worker nodes.
+- Use Readiness and Liveness probes.
+- Register new containers with the Load Balancer only after passing health checks.
+
+---
+
+## 4. Ghaymah Block Storage
+
+Ghaymah Block Storage provides persistent storage for stateful workloads.
+
+Examples:
+
+- PostgreSQL
+- MySQL
+- MongoDB
+- Redis persistence
+- User uploaded files
+
+Benefits:
+
+- Persistent storage after container restart.
+- High availability.
+- Supports snapshots and backups.
+- Suitable for databases and stateful applications.