root_cause_category: storage_exhaustion
required_keywords:
  - storage
  - FreeStorageSpace
required_evidence_sources:
  - aws_rds_events
optimal_trajectory:
  - query_grafana_metrics
  - query_grafana_logs
  - query_grafana_alert_rules
  - describe_rds_instance
  - describe_rds_events
max_investigation_loops: 4
model_response: |
  ROOT_CAUSE: The RDS instance ran out of storage space during a bulk INSERT archival job. FreeStorageSpace collapsed from 15 GB to 0 in 15 minutes driven by elevated WriteIOPS. The RDS control plane confirmed the outage with a "DB instance ran out of storage space" event.
  ROOT_CAUSE_CATEGORY: storage_exhaustion

  VALIDATED_CLAIMS:
  - FreeStorageSpace on orders-prod dropped monotonically from ~15 GB to ~500 MB over 15 minutes. [evidence: aws_cloudwatch_metrics]
  - WriteIOPS peaked at 8100 and then collapsed to near-zero as writes were blocked by the full disk. [evidence: aws_cloudwatch_metrics]
  - RDS event at 02:12:33Z confirmed "DB instance ran out of storage space". [evidence: aws_rds_events]
  - Performance Insights shows an INSERT archival query as the dominant load with IO:DataFileWrite as the top wait event. [evidence: aws_performance_insights]

  NON_VALIDATED_CLAIMS:
  - Expanding storage volume or enabling storage autoscaling would prevent recurrence.

  CAUSAL_CHAIN:
  - A scheduled bulk INSERT archival job ran at 02:00Z writing large volumes of data.
  - WriteIOPS sustained 6000-8100 IOPS depleting the 100 GB volume in 15 minutes.
  - FreeStorageSpace reached 0, causing the RDS engine to reject all further writes.
  - The instance entered an incompatible-restore state and stopped accepting connections.