allocationStrategy

The allocation strategy to use for the compute resource if not enough instances of the best fitting instance type can be allocated. This might be because of availability of the instance type in the Region or Amazon EC2 service limits. For more information, see Allocation strategies in the Batch User Guide.

This parameter isn't applicable to jobs that are running on Fargate resources. Don't specify it.

BEST_FIT (default)

Batch selects an instance type that best fits the needs of the jobs with a preference for the lowest-cost instance type. If additional instances of the selected instance type aren't available, Batch waits for the additional instances to be available. If there aren't enough instances available or the user is reaching Amazon EC2 service limits, additional jobs aren't run until the currently running jobs are completed. This allocation strategy keeps costs lower but can limit scaling. If you're using Spot Fleets with BEST_FIT, the Spot Fleet IAM Role must be specified. Compute resources that use a BEST_FIT allocation strategy don't support infrastructure updates and can't update some parameters. For more information, see Updating compute environments in the Batch User Guide.

BEST_FIT_PROGRESSIVE

Batch selects additional instance types that are large enough to meet the requirements of the jobs in the queue. Its preference is for instance types with lower cost vCPUs. If additional instances of the previously selected instance types aren't available, Batch selects new instance types.

SPOT_CAPACITY_OPTIMIZED

Batch selects one or more instance types that are large enough to meet the requirements of the jobs in the queue. Its preference is for instance types that are less likely to be interrupted. This allocation strategy is only available for Spot Instance compute resources.

SPOT_PRICE_CAPACITY_OPTIMIZED

The price and capacity optimized allocation strategy looks at both price and capacity to select the Spot Instance pools that are the least likely to be interrupted and have the lowest possible price. This allocation strategy is only available for Spot Instance compute resources.

With BEST_FIT_PROGRESSIVE,SPOT_CAPACITY_OPTIMIZED and SPOT_PRICE_CAPACITY_OPTIMIZED (recommended) strategies using On-Demand or Spot Instances, and the BEST_FIT strategy using Spot Instances, Batch might need to exceed maxvCpus to meet your capacity requirements. In this event, Batch never exceeds maxvCpus by more than a single instance.