Domain 2 of 4 · Chapter 6 of 6

Cost optimization for new solutions

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Included in this chapter:

  • Rightsizing and compute selection before any commitment
  • Purchase options: On-Demand, Spot, Savings Plans, RIs
  • Serverless and scale-to-zero cost models
  • Storage tiering and data-transfer cost design
  • Exam patterns: reading the cost question and the distractors

S3 storage-class selection for cost-optimized new solutions

AttributeS3 StandardS3 Standard-IAS3 Intelligent-TieringS3 Glacier Flexible RetrievalS3 Glacier Deep Archive
Best forFrequent, hot accessInfrequent but rapid accessUnknown / changing accessArchive, occasional restoreLong-term cold archive
Retrieval feeNonePer-GB retrieval feeNone (auto-tiering)Per-GB + restore jobPer-GB + restore job
Min storage durationNone30 daysNone90 days180 days
Min billable object sizeActual size128 KBSkips objects <128 KB128 KB (Glacier IR)Per Glacier pricing
Retrieval latencyMillisecondsMillisecondsMilliseconds (frequent/infrequent tiers)Minutes to hoursUp to 12 hours
AZ resilienceMulti-AZ (>=3 AZs)Multi-AZ (>=3 AZs)Multi-AZ (>=3 AZs)Multi-AZ (>=3 AZs)Multi-AZ (>=3 AZs)

Decision tree

Compute or storage decision? Compute Storage (S3) Tolerates interruption (stateless / batch)? Yes Spot Instances up to 90% off, 2-min notice No Steady 24/7 baseline with usage history? Yes Compute Savings Plan up to 66%, flexes (EC2/Fargate/Lambda) No Spiky / unpredictable or new product? Yes Serverless / scale-to-zero Lambda, Fargate, Aurora Serverless v2 No On-Demand measure, then commit later Access pattern known? Yes Lifecycle to IA / Glacier scheduled transitions No S3 Intelligent-Tiering auto-tier (skip <128 KB) Always: rightsize with Compute Optimizer + prefer Graviton before committing
Cheat sheet

Cheat sheet

  • Measure and rightsize before buying any commitment
  • Compute Optimizer rightsizes from 14 days of utilization metrics
  • Graviton: up to 20% lower cost and up to 60% less energy
  • Compute Savings Plan saves up to 66% and is the most flexible
  • EC2 Instance Savings Plan / Standard RI reach up to 72%
  • Spot saves up to 90% but can be reclaimed on a 2-minute notice
  • Blend purchase options by workload segment
  • Operationalize Spot via an ASG mixed instances policy or AWS Batch
  • Lambda bills per request plus GB-seconds, nothing when idle
  • Fargate is serverless containers billed per vCPU/memory-second
  • Aurora Serverless v2 scales to 0 ACUs for pause-on-idle
  • DynamoDB on-demand has no provisioned floor
  • Decoupling with SQS enables scale-to-zero
  • Auto scaling pays for the curve, not the peak rectangle
  • S3 Intelligent-Tiering skips objects under 128 KB
  • S3 storage-class minimums: durations and 128 KB billable size
  • Default EBS to gp3, not gp2
  • EFS Infrequent Access lifecycle plus Elastic throughput cut cost
  • Gateway VPC endpoints for S3/DynamoDB are free and bypass NAT
  • Keep chatty traffic same-AZ to avoid inter-AZ transfer charges
  • A Compute Savings Plan is a $/hour commitment that auto-applies across compute

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References

  1. What is AWS Compute Optimizer?
  2. AWS Graviton Processor: price-performance for cloud workloads
  3. Savings Plans plan types (Compute, EC2 Instance, SageMaker)
  4. Amazon EC2 Spot Instances
  5. AWS Lambda quotas (memory, execution, payload limits)
  6. Amazon ECS task definitions for AWS Fargate
  7. Using Aurora Serverless v2
  8. Amazon DynamoDB on-demand capacity pricing
  9. Amazon S3 storage classes
  10. Amazon S3 Intelligent-Tiering storage class
  11. Amazon EBS general purpose volumes (gp2 and gp3)
  12. Gateway VPC endpoints for Amazon S3 and DynamoDB
  13. AWS Well-Architected Framework: Cost Optimization pillar
  14. Lambda instruction set architectures (arm64/Graviton, x86_64)
  15. What is Amazon EC2 Auto Scaling?
  16. Amazon EC2 Spot Instance interruption notices
  17. Auto Scaling groups with multiple instance types (mixed instances policy)
  18. What is AWS Batch?
  19. AWS Fargate capacity providers (Fargate Spot)
  20. What is Amazon Simple Queue Service?
  21. Managing the lifecycle of objects in Amazon S3
  22. Amazon EFS storage classes and lifecycle management
  23. NAT gateways
  24. Amazon CloudFront pricing