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The following AWS services support either reserved nodes size flexibility or Reserved Instances size flexibility:

*   [Amazon Elastic Compute Cloud (Amazon EC2)](https://aws.amazon.com/ec2/pricing/reserved-instances/). For more information, see [How Reserved Instances are applied](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/apply_ri.html).
*   [Amazon Relational Database Services (Amazon RDS)](https://docs.aws.amazon.com/whitepapers/latest/cost-optimization-reservation-models/amazon-rds-reserved-db-instances.html). For more information, see [Reserved DB instances for Amazon RDS](https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/USER_WorkingWithReservedDBInstances.html).
*   [Amazon DynamoDB](https://docs.aws.amazon.com/whitepapers/latest/cost-optimization-reservation-models/amazon-dynamodb-reservations.html). For more information, see [Amazon DynamoDB reservations](https://docs.aws.amazon.com/whitepapers/latest/cost-optimization-reservation-models/amazon-dynamodb-reservations.html).
*   [Amazon MemoryDB](https://docs.aws.amazon.com/memorydb/latest/devguide/nodes.reservednodes.html). For more information, see [Overview of reserved nodes](https://docs.aws.amazon.com/memorydb/latest/devguide/nodes.reservednodes.html#reserved-nodes-overview).

For reserved nodes or Reserved Instances that are used and don't support size flexibility, you might incur additional charges.

**Important:** Amazon ElastiCache reserved nodes, Amazon OpenSearch Service Reserved Instances, and Amazon Redshift reserved nodes don't support size flexibility.

### Example: Service that supports size flexibility

Suppose you have an EC2 Regional Reserved Instance m5.2xlarge in a specific AWS Region, and the instance supports instance size flexibility. In the same Region, your discounted rate might apply towards the usage of one m5.2xlarge instance or two m5.xlarge instances.

### Example: Service that doesn't support size flexibilty

Suppose you have purchased six cache.r6g.large ElastiCache reserved nodes in a specific Region. In the same Region, you have three cache.r6g.2xlarge nodes running with the same engine type as the reserved node. If there aren't any other r6g family nodes running, then there's no match for your Reserved Instances.

If you purchase ten cache.r6g.large reserved nodes, and have four cache.r6g.2xlarge nodes and two cache.r6g.large nodes running, then only two cache.r6g.large nodes match. For all other nodes that don't match, size flexibility isn't supported.

**Note:** OpenSearch Service and Amazon Redshift follow the same logic as seen in the preceding examples. For DynamoDB, you reserve read and write throughput capacity, not a reserve node or reserve instance.

Related information
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[ElastiCache reserved nodes](https://docs.aws.amazon.com/AmazonElastiCache/latest/red-ug/CacheNodes.Reserved.html)

[Purchasing Amazon Redshift reserved nodes](https://docs.aws.amazon.com/redshift/latest/mgmt/purchase-reserved-node-instance.html)

[Reserved Instances in Amazon OpenSearch Service](https://docs.aws.amazon.com/opensearch-service/latest/developerguide/ri.html)

I want to know what AWS Services support reserved nodes size flexibility or Reserved Instances size flexibility. 

AWS Services that support reserved nodes size flexibility or reserved instances size flexibility

What AWS Services support reserved nodes size flexibility or Reserved Instances size flexibility?

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What AWS Services support reserved nodes size flexibility or Reserved Instances size flexibility?

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Example: Service that supports size flexibility

Example: Service that doesn't support size flexibilty

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