When AWS drops the price of an EC2 instance, they usually reduce both the on-demand and RI/SP discounted price. Lower on-demand rates immediately apply (generally retroactive to the beginning of the month), however, RI price drops do NOT automatically propagate to existing RIs. New RIs receive lower pricing but existing RIs remain at the discounted hourly price at the time of commitment.
If you have existing Standard RIs, you are stuck with the higher price (and will have a difficult time selling them on the RI marketplace since the hourly rate is now higher) but, for existing Convertible RIs, you can exchange them for new RIs of the same type that have the lower hourly price. This is another benefit of Convertible over Standard RIs.
ProsperOps algorithms are always seeking to maximize your savings within the constraints you define, including price changes. We actively monitor for EC2 price drops and will automatically exchange out convertible RIs that have old, more expensive pricing to ensure you get the most savings.
Also, when we assume management of an existing RI portfolio, we examine all RIs against then current pricing and will exchange any Convertible RIs that have old pricing.
While most AWS users don’t exchange Convertible RIs to benefit from price drops, it’s built-in and automatic with ProsperOps.