AWS Savings Plans: SAA-C03 Study Guide
AWS Savings Plans are a flexible pricing model that offers significant savings (up to 72%) over On-Demand pricing in exchange for a commitment to a consistent amount of usage (measured in $/hour) for a 1 or 3-year term.
The Real-World Analogy
Think of a Savings Plan like a Commuter Rail Pass. Instead of buying individual tickets (On-Demand) every time you ride, you commit to spending $50 a month. Whether you take the express train, the local bus, or the subway, your $50 commitment covers those costs at a discounted rate. If you don’t travel enough to meet the $50, you still pay the $50. If you travel more, the excess is charged at the standard rate.
Core Concepts & Plan Types
Unlike Reserved Instances (RIs), which are tied to specific infrastructure attributes, Savings Plans focus on monetary commitment per hour.
- Compute Savings Plans: The most flexible. Applies to EC2 (any family, any region), AWS Fargate, and AWS Lambda.
- EC2 Instance Savings Plans: Deepest discounts. Tied to a specific instance family in a specific region (e.g., M5 in us-east-1), but flexible across sizes (m5.large to m5.xlarge) and OS (Linux/Windows).
- SageMaker Savings Plans: Specifically for Amazon SageMaker usage.
Comparison Table: Savings Plans vs. Reserved Instances
| Feature | Compute Savings Plans | EC2 Instance Savings Plans | Standard RIs |
|---|---|---|---|
| Flexibility | Highest (Region, Family, OS, Service) | Medium (Size, OS, Tenancy) | Low (Specific Config) |
| Services Covered | EC2, Fargate, Lambda | EC2 only | EC2, RDS, ElastiCache, etc. |
| Region Change | Yes | No | No |
| Marketplace Selling | No | No | Yes |
Decision Matrix: If-Then Guide
- IF you have unpredictable workloads that move between regions… THEN choose Compute Savings Plans.
- IF you use a mix of EC2, Fargate, and Lambda… THEN choose Compute Savings Plans.
- IF you have a steady-state workload on a specific EC2 family (e.g., C5) in one region… THEN choose EC2 Instance Savings Plans for higher discounts.
- IF you need to apply discounts to RDS or Redshift… THEN you must use Reserved Instances (Savings Plans do not apply to RDS yet).
Exam Tips and Gotchas
- Commitment is Hourly: You commit to $X per hour. If you commit to $10/hr and only use $8/hr, you are still billed $10. “Use it or lose it” applies every hour.
- No Marketplace: Unlike Standard RIs, you cannot sell a Savings Plan in the AWS RI Marketplace if you no longer need it.
- AWS Organizations: By default, Savings Plans apply to the account that purchased them first, then “float” to cover usage in other accounts within the same AWS Organization (unless sharing is disabled).
- Lambda & Fargate: If the exam mentions “Serverless cost optimization” or “Fargate discounts,” Compute Savings Plans are almost always the correct answer.
Topics covered:
Summary of key subtopics covered in this guide:
- Difference between Compute and EC2 Instance Savings Plans.
- Application of discounts to Fargate and Lambda.
- Hourly commitment mechanics ($/hr).
- Sharing across AWS Organizations.
- Comparison with Reserved Instances (RIs).
Infographic: Savings Plans Architecture
Integrations:
- AWS Organizations: Share commitment across linked accounts.
- Cost Explorer: Provides recommendations based on past 7, 30, or 60 days.
- Budgets: Alert when usage falls below commitment levels.
Impact:
- No technical impact on performance.
- Scaling up/down doesn’t affect the plan, only how much of the commitment is utilized.
- Ideal for Auto Scaling Groups where minimum capacity is known.
Use Case:
A company migrates their web tier from EC2 to Fargate. With a Compute Savings Plan, the discount automatically follows the workload to Fargate without any manual intervention or “exchange” process required.