# ReservedCapacityOptions
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Defines EC2 Fleet preferences for utilizing reserved capacity when `DefaultTargetCapacityType` is set to `reserved-capacity`. EC2 Fleet can fulfill reserved capacity using On-Demand Capacity Reservations, Capacity Blocks for ML, and interruptible Capacity Reservations.

## Contents
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 ** allocationStrategy **   
The strategy that determines the order in which EC2 Fleet launches instances across the reservation types that you specify. The only supported value is `prioritized`, which launches instances in the priority order that you specify in your launch template overrides. If you don't specify an allocation strategy, instances are launched in a random order.  
Type: String  
Valid Values: `prioritized`   
Required: No

 ** ReservationTypeSet.N **   
The types of Capacity Reservations used for fulfilling the EC2 Fleet request.  
Type: Array of strings  
Valid Values: `on-demand-capacity-reservation | capacity-block | interruptible-capacity-reservation`   
Required: No

 ** reservedCapacityFallbackOptions **   
The fallback behavior for the EC2 Fleet when there is not enough reserved capacity available to meet the target capacity.  
Type: [ReservedCapacityFallbackOptions](API_ReservedCapacityFallbackOptions.md) object  
Required: No

## See Also
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For more information about using this API in one of the language-specific AWS SDKs, see the following:
+  [AWS SDK for C\+\+](https://docs.aws.amazon.com/goto/SdkForCpp/ec2-2016-11-15/ReservedCapacityOptions) 
+  [AWS SDK for Java V2](https://docs.aws.amazon.com/goto/SdkForJavaV2/ec2-2016-11-15/ReservedCapacityOptions) 
+  [AWS SDK for Ruby V3](https://docs.aws.amazon.com/goto/SdkForRubyV3/ec2-2016-11-15/ReservedCapacityOptions)