What's changed: Created DP-420 Chapter 5, completing the textbook (Domain 5: monitoring (Normalized RU Consumption hot-partition detection/status codes 429-449-503-408/server-side latency/Azure Monitor alerts/resource logs diagnostic settings→Log Analytics/cross-partition monitoring); backup and restore (periodic vs continuous/PITR/restore point/restore into a new account); security, data movement, DevOps (service-managed vs CMK Key Vault/Private Endpoint-IP-VNet/control-plane Azure RBAC-data-plane Entra ID RBAC/Always Encrypted/CORS/data movement ADF-Spark-Kafka-Stream Analytics-IoT Hub/DevOps declarative ARM-imperative PowerShell-CLI standard↔autoscale-failover)).
5.1Monitoring and troubleshooting
Understand response status codes and failure metrics, monitoring Normalized RU Consumption and server-side latency with Azure Monitor, replication monitoring, alerts and resource logs, and monitoring throughput/data distribution across partitions.
In operations, surface RU skew, throttling, latency, and availability to catch issues early. Cosmos DB exposes metrics/logs/alerts via Azure Monitor.
5.1.1Key metrics and status codes
Normalized RU Consumption shows the RU utilization (0–100%) of the busiest partition—the key metric to detect a hot partition (consumption skewed to one partition); a sustained high value foreshadows 429s. Response status codes / failure metrics (429 rate limiting, 449 concurrency retry, 503 transient, 408 timeout) classify failures. Server-side latency isolates slowness inside the service (vs client/network causes). Monitor throughput/data distribution across partitions; skew calls for revisiting the partition key design.
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