AWS Reserved Instances - How to read an optimization report

After you have configured the RI Optimisation feature, and the report have been generated, when you click on the name of the report you will have access to the details of the optimization data.

Overview of the Reserved Instance Optimization report

On a dashboard when you clicked the report title you will be redirected to the report details page. The first thing you will see is a summary illustrated by a graph of the RI commitment recommendations:

  1. The number of instances part of the commitment and the breakdown by availability zone. The commitment is by family for Linux/Unix (Flex RI) or type for the other Ec2 instance
  2. You can filter by tags inside the cost partition but also by account, zone, instance type
  3. The parameters which led to those results, see the configuration page for more details.
  4. Toggle filters to show or hide the recommendations for purchase of new RIs, relocations of existing ones and those unused (in red)
  5. Finally the financial summary which gives you the total commitment and the saving expected from the purchase or the relocation in the currency configured for your account or the one of your company

Details of the Reserved Instance Optimization report

Below the summary you will find 4 tables listing the details for each recommendation:

  1. one for the recommendation based on the relocation of RIs
  2. second for the purchase of Reserved Instances
  3. third for the Reserved Instances "Not in the money" i.e. RIs which are not yet break even
  4. finally one for Reserved Instance which are going to expire

Reserved Instances Purchases Recommendations

For the first table (1) you will see the number of instances to add or remove depending of the size.

In the purchases table (2), the savings, commitment and the comparison with the on-demand cost is breakdown by family / instance type in asbolute and relative terms.

If you click on the last column (3), you will see the cost allocation units for those recommendations and a link to a report in the dynamic cost explorer. More details below.

When you click on the last column, you will see the list of cost allocation units and for each the average usage (1). You can access the Reservation report in the Dynamic Cost Explorer by clicking the "graph" button (2).

If you filter by instance type, and enter t2 as the filter value (1), you will see that the Reserved Instance Optimization recommends 0.5 units for the first account (2). If you click on the last column to access the dynamic cost explorer you will see the report as described below.

The dynamic explorer will show you the usage of EC2 instances for the cost allocation unit and the account. You can see here that the On Demand instance usage of t2.family (1) is pretty consistent (2).

Since it's a flexible Reserved Instance we show the values in a normalized manner: a small instance is 1 0.5 being a micro instance.

To see the raw value, i.e. before transformation, you click on the cog button (3) and remove the transformation by selecting "none" as transformation (see below).

Here's another example with instances of type m4.large.windows where you can see the usage of on demande versus reserved :

Reserved Instances "Not In the Money"

List of Reserved Instances that are not break even i.e. for which the usage level doesn't make the commitment worthwile for the period.

If you go to the Dynamic Cost Explorer, choose the Reservations menu and filter with the instance type (1) and group by operation (2) show in the table, you see that the "Unused" usage (3) here in light green, is very large for the period:

Reserved Instances Ignored

This table gives you a list of RI which are going to expire. You can also get an email one month before the RI is going to expire. Please contact us to enable this feature,