Accessing reservation recommendations

If you enable Cost Explorer, you automatically get Amazon EC2, Amazon RDS, ElastiCache, OpenSearch Service, Amazon Redshift, and Amazon MemoryDB Reserved Instance (RI) purchase recommendations that could help you reduce your costs. RIs provide a discounted hourly rate (up to 75%) compared to On-Demand pricing. Cost Explorer generates your RI recommendations using the following process:

• Identifies your On-Demand Instance usage for a service during a specific time period

• Collects your usage into categories that are eligible for an RI

• Simulates every combination of RIs in each category of usage

• Identifies the best number of each type of RI to purchase to maximize your estimated savings

For example, Cost Explorer automatically aggregates your Amazon EC2 Linux, shared tenancy, and c4 family usage in the US West (Oregon) Region and recommends that you buy size-flexible regional RIs to apply to the c4 family usage. Cost Explorer recommends the smallest size instance in an instance family. This makes it easier to purchase a size-flexible RI. Cost Explorer also shows the equal number of normalized units so that you can purchase any instance size that you want. For this example, your RI recommendation would be for c4.large because that is the smallest size instance in the c4 instance family.

Cost Explorer recommendations are based on a single account or organization usage of the past seven, 30, or 60 days. Cost Explorer uses On-Demand instance usage during the selected look-back period to generate recommendations. All other usage in the look-back period that are covered by features such as RI, SPOT, and Savings Plans aren't included. Amazon EC2, ElastiCache, OpenSearch Service, Amazon Redshift, and Amazon MemoryDB recommendations are for RIs scoped to Region, not Availability Zones, and your estimated savings reflects the application of those RIs to your usage. Amazon RDS recommendations are scoped to either Single-AZ or Multi-AZ RIs. Cost Explorer updates your recommendations at least once every 24 hours.

Note

Cost Explorer doesn't forecast your usage or take forecasts into account when recommending RIs. Instead, Cost Explorer assumes that your historical usage reflects your future usage when determining which RIs to recommend.

Linked accounts can see recommendations only if they have the relevant permissions. Linked accounts need permissions to view Cost Explorer and permissions to view recommendations. For more information, see Viewing the Cost Explorer Reservation Recommendations.

RI Recommendations for Size-Flexible RIs

Cost Explorer also considers the benefits of size-flexible regional RIs when generating your RI purchase recommendations. Size-flexible regional RIs help maximize your estimated savings across eligible instance families in your recommendations. AWS uses the concept of normalized units to compare the various sizes within an instance family. Cost Explorer uses the smallest normalization factor to represent the instance type that it recommends. For more information, see Instance Size Flexibility for EC2 Reserved Instances.

For example, let’s say you own an EC2 RI for a c4.8xlarge. This RI applies to any usage of a Linux/Unix c4 instance with shared tenancy in the same region as the RI, such as the following instances:

• One c4.8xlarge instance

• Two c4.4xlarge instances

• Four c4.2xlarge instances

• Sixteen c4.large instances

It also includes combinations of EC2 usage, such as one c4.4xlarge and eight c4.large instances.

If you own an RI that is smaller than the instance that you're running, you are charged the prorated, On-Demand price for the excess. This means that you could buy an RI for a c4.4xlarge, use a c4.4xlarge instance most of the time, but occasionally scale up to a c4.8xlarge instance. Some of your c4.8xlarge usage is covered by the purchased RI, and the rest is charged at On-Demand prices. For more information, see How Reserved Instances Are Applied in the Amazon Elastic Compute Cloud User Guide.

Viewing the Cost Explorer Reservation Recommendations

Linked accounts need the following permissions to view recommendations:

• ViewBilling

• ViewAccount

For more information, see Using identity-based policies (IAM policies) for AWS Cost Management.

To view your RI recommendations

1. Sign in to the AWS Management Console and open the AWS Cost Management console at https://console.aws.amazon.com/cost-management/home.

2. In the navigation pane, under Reservations, choose Recommendations.

3. For Select recommendation type, choose the service that you want recommendations for.

Reading the Cost Explorer RI Recommendations

The RI recommendation page shows you your estimated potential savings, your RI purchase recommendations, and the parameters that Cost Explorer used to create your recommendations. You can change the parameters to get recommendations that might match your use case more closely.

The top of the RI recommendations page show you three numbers:

• Estimated Annual Savings – Your Estimated Annual Savings is how much Cost Explorer calculates that you could save by purchasing all the recommended RIs.

• Savings vs. On-Demand – Your Savings vs. On-Demand is your estimated savings as a percentage of your current costs.

• Purchase Recommendations – Your Purchase Recommendations is how many different RI purchase options that Cost Explorer found for you.

These numbers enable you to see a rough estimate of how much you could potentially save by buying more RIs. You can recalculate these numbers for a different use case by using the parameters in the pane on the right. The pane allows you to change the following parameters:

• RI term – The length of the RI reservation that you want recommendations for.

• Offering class – Whether you want recommendations for a standard RI or a convertible RI.

• Payment option – Whether you want to pay for recommended RIs upfront.

• Based on the past – How many days of your previous instance usage that you want your recommendations to take into account.

At the bottom of the page are tabs with some of your savings estimates. The All accounts tab enables you to see the recommendations based on the combined usage across your entire organization, and the Individual accounts tab enables you to see recommendations that Cost Explorer generated on a per-linked-account basis. The table on each tab shows the different purchase recommendations and details about the recommendations. If you want to see the usage that Cost Explorer based a recommendation on, choose the View associated usage link in the recommendation details. This takes you to a report that shows the exact parameters that Cost Explorer used to generate your recommendation. The report also shows your costs and associated usage grouped by Purchase option, so that you can view the On-Demand Instance usage that your recommendation is based on.

Note

Recommendations that Cost Explorer bases on an individual linked account consider all usage by that linked account, including any RIs used by that linked account. This includes RIs shared by another linked account. The recommendations don't assume that an RI will be shared with the linked account in the future.

You can sort your recommendations by Monthly estimated savings, Upfront RI cost, Purchase recommendation, or Instance type.

Modifying Your RI Recommendations

You can change the information that Cost Explorer uses when it creates your recommendations, and you can also change the types of recommendations that you want. This allows you to see recommendations for the RIs that work best for you, such as All UpFront RIs with a one-year term, based on your last 30 days of usage.

Note

Instead of forecasting your future usage, Cost Explorer assumes that your future usage is the same as your previous usage. Cost Explorer also assumes that you are renewing any expiring RIs.

To modify your RI recommendations

1. Sign in to the AWS Management Console and open the AWS Cost Management console at https://console.aws.amazon.com/cost-management/home.

2. On the navigation bar, choose the menu, choose RI Recommendations and then under Select a service choose the service that you want to modify the recommendations for.

3. In the RI Recommendation Parameters pane, change the parameters that you want to change. Your estimated savings update automatically.

   1. For RI term, select the RI term that you want.

   2. For Offering class, select the RI class that you want.

   3. For Payment option, select the purchase option that you want.

   4. For Recommendation type, select the logic that you want your recommendations based on.

   5. For Based on the past, select how many days of usage that you want your RI recommendations to be based on.

4. Choose either All accounts or Individual accounts to see recommendations based either on your organization-wide usage or on all of your linked accounts based on their individual account usage.

Saving Your RI Recommendations

You can save your RI recommendations as a CSV file.

To save your RI recommendations

1. On the Reserved Instance Recommendations page, in the RI parameter pane, change any parameters that you want to change. Your estimated savings update automatically.

2. Above the recommendation table, choose Download CSV.

The CSV file contains the following columns.

RI Recommendation CSV Columns
Column Name	Service	Column Explanation
Account ID	Amazon EC2, RDS, Redshift, ElastiCache, OpenSearch Service, MemoryDB	The account associated with your recommendation.
Availability zone	Amazon RDS	The availability zone of the instances used to generate a recommendation.
Average hourly normalized unit usage in historical period	Amazon EC2, RDS, MemoryDB	The average number of normalized units used per hour over the period chosen for generating recommendations.
Average hourly usage in historical period	Amazon EC2, RDS, Redshift, ElastiCache, OpenSearch Service, MemoryDB	The average number of instance hours used per hour over the period chosen for generating recommendations.
Break even months	Amazon EC2, RDS, Redshift, ElastiCache, OpenSearch Service, MemoryDB	The estimated length of time before you recoup your upfront costs for this set of recommended reservations.
Cache engine	Amazon ElastiCache	The kind of engine that the recommended ElastiCache reserved node runs, such as Redis or Memcheched.
Database edition	Amazon RDS	The edition of the database engine that the recommended RDS reserved instance runs.
Database engine	Amazon RDS	The kind of engine that the recommended RDS RI runs, such as Aurora MySQL or MariaDB.
Deployment option	Amazon RDS	Whether your RI is for an RDS instance in a single Availability Zone or an RDS instance with a backup in another Availability Zone.
Estimated savings	Amazon EC2, RDS, Redshift, ElastiCache, OpenSearch Service, MemoryDB	The estimated savings of the recommended reservations.
Expected utilization	Amazon EC2, RDS, Redshift, ElastiCache, OpenSearch Service, MemoryDB	How much of the recommended RI Cost Explorer estimates you will use.
Instance type	Amazon EC2, RDS, OpenSearch Service	The type of instance that the recommendation is generated for (for example, m4.large or t2.nano). For size-flexible recommendations, Cost Explorer aggregates all usage in a organization (for example, the m4 family) and shows a recommendation for the smallest instance type RI that is available for purchase (for example, m4.large).
Max hourly normalized unit usage in historical period	Amazon EC2, RDS, MemoryDB	The maximum number of normalized units used in an hour over the period chosen for generating recommendations.
Max hourly usage in historical period	Amazon EC2, RDS, Redshift, ElastiCache, OpenSearch Service, MemoryDB	The maximum number of instance hours used in an hour over the period chosen for generating recommendations.
Min hourly normalized unit usage in historical period	Amazon EC2, RDS, MemoryDB	The minimum number of normalized units used in an hour over the period chosen for generating recommendations.
Min hourly usage in historical period	Amazon EC2, RDS, Redshift, ElastiCache, OpenSearch Service, MemoryDB	The minimum number of instance hours used in an hour over the period chosen for generating recommendations.
Node type	Amazon ElastiCache, Redshift, MemoryDB	The type of node that the recommendation is generated for, such as ds2.xlarge.
Normalized hours to purchase	Amazon EC2, RDS, MemoryDB	How many normalized units that Cost Explorer recommends that you buy.
Number of instances to purchase	Amazon EC2, RDS, Redshift, ElastiCache, OpenSearch Service, MemoryDB	How many reservations Cost Explorer recommends that you buy.
Offering class	Amazon EC2	The offering class associated with your recommendation.
Payment option	Amazon EC2, RDS, Redshift, ElastiCache, OpenSearch Service, MemoryDB	The recommended payment option for the recommendation.
Platform	Amazon EC2	The operating system and license model for the recommended RI instance type.
Recommendation date	Amazon EC2, RDS, Redshift, ElastiCache, OpenSearch Service, MemoryDB	The date that Cost Explorer generated your recommendation.
Recurring monthly cost	Amazon EC2, RDS, Redshift, ElastiCache, OpenSearch Service, MemoryDB	The recurring monthly cost of the recommended reservations.
Region	Amazon EC2, RDS, Redshift, ElastiCache, OpenSearch Service, MemoryDB	The region of the instances used to generate a recommendation. You must purchase the recommended RIs in the recommended region to see potential savings.
Size flexible	Amazon EC2, RDS, MemoryDB	Whether a recommended RI is size-flexible.
Tenancy	Amazon EC2	The tenancy for the recommended RI purchase. Valid values are shared or dedicated.
Term	Amazon EC2, RDS, Redshift, ElastiCache, OpenSearch Service, MemoryDB	The recommended term length for the recommendation.

Using Your RI Recommendations

To purchase the recommended reservations, go to the purchase page on a service console. You can also save a CSV file of your recommendations and purchase the reservations at a later date.

To use Amazon Elastic Compute Cloud recommendations

1. On the Reserved Instance Recommendations page, choose Amazon EC2 RI Purchase Console to go to the Amazon EC2 Purchase Console.

2. Purchase your RIs by following the instructions at Buying Reserved Instances in the Amazon EC2 User Guide.

To use Amazon Relational Database Service recommendations

1. On the Reserved instances page in the Amazon RDS console, choose Purchase Reserved DB Instance.

2. Purchase your reservations by following the instructions at Working with reserved DB instances in the Amazon RDS User Guide.

To use Amazon Redshift recommendations

1. On the Reserved nodes page in the Amazon Redshift console, choose Purchase reserved nodes.

2. Purchase your reservations by following the instructions at Purchasing a reserved node offering with the Amazon Redshift console in the Amazon Redshift Management Guide.

To use Amazon OpenSearch Service recommendations

1. On the Reserved Instance Leases page in the OpenSearch Service console, choose Order Reserved Instance.

2. Purchase your reservations by following the instructions at Reserved Instances in Amazon OpenSearch Service in the Amazon OpenSearch Service Developer Guide.

To use Amazon ElastiCache recommendations

1. On the Reserved Nodes page in the ElastiCache console, choose Purchase reserved nodes.

2. Purchase your reservations by following the instructions at Purchasing a Reserved Node in the Amazon ElastiCache User Guide.

To use Amazon MemoryDB recommendations

1. On the Reserved nodes page in the MemoryDB console, choose Purchase reserved nodes.

2. Purchase your reservations by following the instructions at Working with reserved nodes in the Amazon MemoryDB Developer Guide.