Workload Rightsizing And Capacity Optimization — AWS SysOps Administrator (SOA-C03)
Average CPU Utilization Hides the Burst Story
Low average CPU utilization can mean the instance is oversized — or that the workload is bursty and the peak is what matters. Candidates who read average utilization as the only signal will downsize a workload that cannot tolerate capacity gaps during bursts. The exam expects you to use Compute Optimizer recommendations alongside CloudWatch p99 metrics, not averages, to determine whether rightsizing is safe for the given traffic pattern.
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 absorb burst CPU demand by permanently over-provisioning a fixed large memory-optimized instance or by configuring an Auto Scaling group with a compute-optimized instance family sized to the actual bottleneck metric, satisfying the cost ceiling by paying only for burst capacity when needed.
Whether to absorb burst CPU demand by vertically upsizing to a permanently running oversized instance or by horizontally scaling a right-family (compute-optimized) Auto Scaling group scoped only to burst duration.
Choose between AWS Compute Optimizer — which ingests CloudWatch utilization metrics and applies ML models to recommend specific instance families with performance risk projections — and AWS Cost Explorer — which analyzes billing data and offers a coarse rightsizing tab — given an explicit requirement for metric-granular, automated instance-type recommendation based on historical utilization data.
Domain Coverage
Difficulty Breakdown