Workload Rightsizing And Capacity Optimization — AWS Solutions Architect Pro (SAP-C02)
Rightsize First, Then Commit Reserved Capacity
Purchasing Reserved Instances or Savings Plans before analyzing actual utilization locks spend at the current, potentially over-provisioned instance size. AWS Compute Optimizer requires at least 14 days of CloudWatch utilization metrics to generate statistically valid resize recommendations. Applying commitment pricing before that data exists embeds waste into a one- or three-year financial obligation. The correct sequence is: instrument with CloudWatch, collect at least 14 days of data, rightsize using Compute Optimizer recommendations, then apply Reserved Instance or Savings Plan commitments to the rightsized fleet. SAP-C02 questions test whether you recognize rightsizing and commitment purchasing as sequential, dependent steps rather than independent optimizations that can run in either order.
What This Pattern Tests
The exam presents an over-provisioned or under-provisioned workload and tests whether you identify the rightsizing opportunity. AWS Compute Optimizer analyzes CPU, memory, and network metrics to recommend instance type changes. CloudWatch metrics show utilization history. The trap is recommending Reserved Instances for an over-provisioned instance — you save 40% on a $200/month instance ($80 savings) when rightsizing first saves 75% ($150 savings) and then you reserve the smaller instance. Always rightsize before applying pricing optimizations.
Decision Axis
Current utilization vs. provisioned capacity. Rightsize first (reduce waste), then optimize pricing (reduce rate).
Associated Traps
More Top Traps on This Exam
Decision Rules
Whether to apply Savings Plans commitment to the existing m5.2xlarge fleet immediately (capturing the SP discount but preserving the over-provisioned instance type), or to use AWS Compute Optimizer utilization recommendations to downsize the instance type first and then apply Savings Plans to the right-sized fleet, capturing both the sizing saving and the pricing-model discount.
Domain Coverage
Difficulty Breakdown