Design a Distributed Logging & Monitoring System

Architect a **distributed logging and monitoring system** like ELK or Datadog.

Include:
1. Log ingestion pipeline (agents → collectors → brokers)
2. Storage format + compression strategy
3. Query indexing strategy
4. Alerting rules engine
5. Visualization dashboards
6. Cardinality management
7. Multi-tenant isolation model
8. Log retention + tiering strategy
9. On-call SLO/SLI alignment
10. Cost-optimization techniques for high-volume logs