Reserved node pricing is less expensive than on-demand pricing because compute nodes are billed at discounted hourly rates. However, to receive these discounted rates, you must purchase reserved node offerings. When you purchase an offering, you make a reservation. The reservation sets a discounted rate for each node that you reserve for the duration of the reservation.
The discounted rate in an offering varies depending on factors such as the region, node type, duration, and payment option.
Rule Description
In the evaluation phase of your project or when you're developing a proof of concept, on-demand pricing gives you the flexibility to pay as you go, to pay only for what you use, and to stop paying at any time by shutting down or deleting clusters. After you have established the needs of your production environment and begin the implementation phase, you should consider reserving compute nodes by purchasing one or more offerings.
Rule Description
Rule Code: AWS-R-RS-02
Checks your usage of RedShift and provides recommendations on purchase of Reserved Nodes to help reduce costs incurred from using RedShift On-Demand.
Recommendation
An offering can apply to one or more compute nodes. You specify the number of compute nodes to reserve when you purchase the offering. You might choose to purchase one offering for multiple compute nodes, or you might choose to purchase multiple offerings and specify a certain number of compute nodes in each offering.
For example, any of the following are valid ways to purchase an offering for three compute nodes:
- Purchase one offering and specify three compute nodes.
- Purchase two offerings, and specify one compute node for the first offering and two compute nodes for the second offering.
- Purchase three offerings, and specify one compute node for each of the offerings.
Comparing pricing among reserved node offerings
Amazon Redshift provides several payment options for offerings. The payment option that you choose affects the payment schedule and the discounted rate that you are charged for the reservation. The more that you pay upfront for the reservation, the better the overall savings are.
The following payment options are available for offerings. The offerings are listed in order from least to most savings over on-demand rates.
Reference
https://docs.aws.amazon.com/redshift/latest/mgmt/purchase-reserved-node-instance.html