# OnDemandProvisioningSpecification
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 The launch specification for On-Demand Instances in the instance fleet, which determines the allocation strategy. 

**Note**  
The instance fleet configuration is available only in Amazon EMR releases 4.8.0 and later, excluding 5.0.x versions. On-Demand Instances allocation strategy is available in Amazon EMR releases 5.12.1 and later.

## Contents
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 ** AllocationStrategy **   <a name="EMR-Type-OnDemandProvisioningSpecification-AllocationStrategy"></a>
Specifies the strategy to use in launching On-Demand instance fleets. Available options are `lowest-price` and `prioritized`. `lowest-price` specifies to launch the instances with the lowest price first, and `prioritized` specifies that Amazon EMR should launch the instances with the highest priority first. The default is `lowest-price`.  
Type: String  
Valid Values: `lowest-price | prioritized`   
Required: Yes

 ** CapacityReservationOptions **   <a name="EMR-Type-OnDemandProvisioningSpecification-CapacityReservationOptions"></a>
The launch specification for On-Demand instances in the instance fleet, which determines the allocation strategy.  
Type: [OnDemandCapacityReservationOptions](API_OnDemandCapacityReservationOptions.md) object  
Required: No

## See Also
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For more information about using this API in one of the language-specific Amazon SDKs, see the following:
+  [Amazon SDK for C\$1\$1](https://docs.amazonaws.cn/goto/SdkForCpp/elasticmapreduce-2009-03-31/OnDemandProvisioningSpecification) 
+  [Amazon SDK for Java V2](https://docs.amazonaws.cn/goto/SdkForJavaV2/elasticmapreduce-2009-03-31/OnDemandProvisioningSpecification) 
+  [Amazon SDK for Ruby V3](https://docs.amazonaws.cn/goto/SdkForRubyV3/elasticmapreduce-2009-03-31/OnDemandProvisioningSpecification)