AWS Certified Solutions Architect Professional SAP-C02 Practice Question

The correct approach is to purchase a 3-year, All Upfront Compute Savings Plan for the baseline usage and use Spot Instances, supplemented by On-Demand Instances, for the spiky workloads.

• Compute Savings Plans offer the most flexibility, automatically applying discounts across different instance families, sizes, operating systems, and AWS Regions. This directly addresses the requirement to adopt new instance families without manual intervention, which would be required with Convertible RIs. Committing to a 3-year term with an all-upfront payment provides the maximum possible discount for the predictable baseline usage.
• Standard Reserved Instances are not suitable because they lock the user into a specific instance family, which contradicts the flexibility requirement.
• EC2 Instance Savings Plans are also less suitable than Compute Savings Plans because they are restricted to a single instance family within a specific AWS Region, offering less flexibility.
• For the unpredictable, spiky workloads, Spot Instances are the most cost-effective choice, offering discounts of up to 90% off On-Demand prices for fault-tolerant workloads. On-Demand instances can supplement Spot Instances for any workloads that cannot be interrupted. Using Capacity Reservations is not a cost-optimization strategy, as it only reserves capacity at On-Demand rates without providing a discount.