Rebalancing Convertible RIs – Solve your reduced AWS demand problems

Written by Aditya Datta

In times of uncertainty, how to effectively manage cash flow and OpEx is a top concern for all leaders. If your organization is dealing with reduced customer demand and AWS consumption, you can reduce your monthly spending commitment with AWS by Rebalancing your existing fleet of convertible reserved instances.

How does rebalance work?

Our customers are able to rebalance their Convertible RIs similar to how a homeowner can refinance a 15-year mortgage to a full term 15, 20 or 30-year mortgage and reduce monthly payments.

When you merge two convertible RIs, the new one will have:

  • The best terms (if you’re mixing 1-year and 3-years, it will result in 3-years).
  • The longest duration (the end-date of the new RI will be the max of both source end-dates).
  • The total remaining contract value needs to be equal or bigger.

You have several choices to rebalance:

  • Purchase a new RI with a longer duration than the remaining unused RIs. We use t3a.nanos for this as they are the cheapest.
  • Merge existing RIs with different durations (and you will extend the duration of the short one to the largest one).

In both cases, the new total contract value will be pretty much the same as the source, but the duration will be higher, so the monthly amount will be lower.

Consider the following example: we have some unused x1.16xlarge we want to rebalance. At the end of the rebalance operation, we will have fewer monthly hours reserved for x1.16xlarge usage, so we will pay less.
Refinance Table

We moved from 15 x1.16xlarge instances to 8 x1.16xlarge instances to meet the reduced demand. Not only have we reduced our monthly bill by $36.8k, but our hourly cost has also been decreased!! (from 4.726 to 2.465, almost a 48% decrease over the already reduced price of the CRI). By the way, if the workload decreases again in the next two months, we can extend the 34 remaining months to 36 months again. ($14,198* 34/36 = $13,409).

Adjusting these numbers to the real demand can be really hard to be done manually, and we will be happy to discuss this in more details, our Savings Autopilot has been doing this for multiple years and manages your reserved instances and savings plans automatically based on guardrails that you establish.