Domain 3 of 4 · Chapter 5 of 5

Improving cost optimization

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Included in this chapter:

  • The measure-find-act loop for existing spend
  • Discovery tools: rightsizing and idle-resource detection
  • Commitment discounts: Savings Plans, RIs, and Spot
  • Reclaiming waste: idle resources, storage, and Graviton
  • Accountability, anomaly detection, and exam patterns

Cost-optimization discovery tools by what they find

ToolPrimary findingScopeCost to use
Cost Explorer rightsizingUnderutilized / idle EC2 to downsize or terminateEC2 across linked accounts; uses Compute Optimizer dataConsole free; CE API $0.01 per request
AWS Compute OptimizerOver-provisioned / idle EC2, ASG, EBS, LambdaPer-account, opt-in; ML on CloudWatch metricsFree (default metrics)
AWS Trusted AdvisorIdle ELB, unassociated EIP, unattached EBS, idle RDS / NAT, RI & SP recsAccount-wide cost checksFull checks (incl. cost) need Business Support+/Enterprise/Unified Ops
S3 Storage LensBuckets missing lifecycle rules; cold prefixesOrg / account / bucket / prefix object storageFree tier (14-day); advanced tier paid (15-month)
Cost Anomaly DetectionUnexpected cost spikes vs ML baselinePer service / account / cost category / tag monitorFree

Decision tree

What is the cost symptom? on an existing workload Compute over-sized or idle? Steady baseline to rate-reduce? Storage or unexpected spike? Resources Rate Storage / spike Compute Optimizer / Cost Explorer rightsizing downsize the fleet Trusted Advisor delete idle ELB / EIP / EBS / RDS / NAT Over-provisioned Idle / orphaned Savings Plans / RIs Compute SP = flexible (66%) EC2 Instance SP = 72% Spot Instances up to 90% off; 2-min notice interruption-tolerant only Predictable, always-on Interruptible / batch S3 Intelligent-Tiering / S3 Storage Lens tier & find cold data Cost Anomaly Detection ML spike alerts (free); monitor svc / acct / tag Growing S3 bill Unexpected spike Always: rightsize before you commit, and tag for cost accountability + showback Graviton migration (up to 20% lower cost (and up to 60% less energy)) applies across compute
Cheat sheet

Cheat sheet

  • Rightsize before you commit to reserved capacity
  • Compute Optimizer finds over-provisioned and idle compute
  • Cost Explorer rightsizing downsizes or terminates EC2 by dollars
  • Cost Optimization Hub consolidates savings recommendations
  • Trusted Advisor flags idle and orphaned resources
  • Compute Savings Plans are flexible at up to 66% off
  • EC2 Instance Savings Plans reach 72% but lock the family
  • Run interruption-tolerant work on EC2 Spot
  • Reserved capacity still covers databases and caches
  • Read utilization and coverage to size the commitment
  • Unattached EBS and idle Elastic IPs keep billing
  • Idle NAT gateways bill per hour plus per GB
  • Automate snapshot expiry with Data Lifecycle Manager
  • Intelligent-Tiering skips objects under 128 KB
  • Storage Lens free tier vs advanced tier
  • Graviton cuts cost up to 20% for the same performance
  • Stop off-hours dev/test with Instance Scheduler
  • Cost Anomaly Detection is free and ML-based
  • Anomaly Detection finds spikes; Budgets enforces thresholds
  • Anomaly alerts come individual, daily, or weekly
  • Gateway VPC endpoints for S3 and DynamoDB bypass NAT charges
  • Reservations and Savings Plans apply in a fixed order
  • On-Demand Capacity Reservations guarantee capacity, not a discount
  • Cost Anomaly Detection monitors by service, account, category, or tag

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Also tested in

References

  1. What is AWS Compute Optimizer?
  2. Optimizing your cost with rightsizing recommendations (Cost Explorer)
  3. Savings Plans plan types
  4. Cost optimization checks (AWS Trusted Advisor)
  5. Understanding Amazon S3 Storage Lens
  6. S3 Intelligent-Tiering storage class
  7. Using AWS cost allocation tags
  8. Getting started with AWS Cost Anomaly Detection
  9. AWS Well-Architected Framework: Cost Optimization Pillar Well-Architected
  10. Cost Optimization Hub
  11. Reserved Instances for Amazon EC2
  12. Use Amazon EC2 Spot Instances
  13. Amazon EC2 Spot Instance interruptions
  14. Gateway endpoints (VPC)
  15. Amazon Data Lifecycle Manager
  16. AWS Graviton Processor
  17. Instance Scheduler on AWS
  18. AWS Organizations tag policies