Which change in instance type will meet these requirements?
Change to one large compute optimized On-Demand Instance.
Change to one large memory optimized On-Demand Instance.
Change to one xlarge general purpose Spot Instance.
Change to two large general purpose On-Demand Instances.
Explanations:
A compute optimized instance is designed for high CPU performance, but the current workload uses only 40% CPU and 80% memory, so this change would not optimize the cost effectively.
A memory optimized instance would provide more memory resources, which aligns with the current memory usage of 80%, potentially lowering costs without negatively affecting performance.
Spot instances offer lower cost, but they are not guaranteed to be available long-term and could lead to interruptions, which is unsuitable for a stateful, long-running workload.
Splitting the workload into two instances might introduce unnecessary complexity and additional costs compared to simply resizing to a more appropriate instance type.
I calculate that the answer is:
Change to one large memory optimized On-Demand Instance.