# Use Amazon EC2 Spot best practices for AWS Batch
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When you choose Amazon Elastic Compute Cloud (EC2) Spot instances, you likely can optimize your workflow to save costs, sometimes significantly. For more information, see [Best practices for Amazon EC2 Spot](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/spot-best-practices.html#be-instance-type-flexible).

To optimize your workflow to save costs, consider the following Amazon EC2 Spot best practices for AWS Batch:
+ **Choose the `SPOT_CAPACITY_OPTIMIZED` allocation strategy** – AWS Batch chooses Amazon EC2 instances from the deepest Amazon EC2 Spot capacity pools. If you’re concerned about interruptions, this is a suitable choice. For more information, see [Instance type allocation strategies for AWS Batch](allocation-strategies.md).
+ **Diversify instance types** – To diversify your instance types, consider compatible sizes and families, then let AWS Batch choose based on price or availability. For example, consider `c5.24xlarge` as an alternative to `c5.12xlarge` or `c5a`, `c5n`, `c5d`, `m5`, and `m5d` families. For more information, see [Be flexible about instance types and Availability Zones](https://docs.aws.amazon.com/AWSEC2/latest/WindowsGuide/spot-best-practices.html#be-instance-type-flexible).
+ **Reduce job runtime or checkpoint** – We advise against running jobs that take an hour or more when using Amazon EC2 Spot instances to avoid interruptions. If you divide or checkpoint your jobs into smaller parts that consist of 30 minutes or less, you can significantly reduce the possibility of interruptions.
+ **Use automated retries** – To avoid disruptions to AWS Batch jobs, set automated retries for jobs. Batch jobs can be disrupted for any of the following reasons: a non-zero exit code is returned, a service error occurs, or an instance reclamation occurs. You can set up to 10 automated retries. For a start, we recommend that you set at least 1-3 automated retries. For information about tracking Amazon EC2 Spot interruptions, see [Spot Interruption Dashboard](https://github.com/aws-samples/ec2-spot-interruption-dashboard).

  For AWS Batch, if you set the retry parameter, the job is placed at the front of the job queue. That is, the job is given priority. When you create the job definition or you submit the job in the AWS CLI, you can configure a retry strategy. For more information, see [submit-job](https://docs.aws.amazon.com/goto/aws-cli/batch-2016-08-10/SubmitJob       ).

  ```
  $ aws batch submit-job --job-name MyJob \
      --job-queue MyJQ \
      --job-definition MyJD \
      --retry-strategy attempts=2
  ```
+ **Use custom retries** – You can configure a job retry strategy to a specific application exit code or instance reclamation. In the following example, if the host causes the failure, the job can be retried up to five times. However, if the job fails for a different reason, the job exits and the status is set to `FAILED`.

  ```
  "retryStrategy": {
      "attempts": 5,
      "evaluateOnExit":
      [{
          "onStatusReason" :"Host EC2*",
          "action": "RETRY"
      },{
        "onReason" : "*",
          "action": "EXIT"
      }]
  }
  ```
+ **Use the Spot Interruption Dashboard** – You can use the Spot Interruption Dashboard to track Spot interruptions. The application provides metrics on Amazon EC2 Spot instances that are reclaimed and which Availability Zones that Spot instances are in. For more information, see [Spot Interruption Dashboard](https://github.com/aws-samples/ec2-spot-interruption-dashboard) 
+ **Enable Amazon ECS Spot Instance draining (default for new or updated compute environments as of October 9, 2026)** – For compute environments that use Amazon ECS and Spot Instances, AWS Batch enables Spot Instance draining by default. When Amazon EC2 issues a two-minute Spot Instance interruption notice, the container instance is set to `DRAINING`, which allows existing jobs to continue but prevents new jobs from being placed on the instance. For more information about Spot Instance draining, see the *Amazon Elastic Container Service Developer Guide* pages on [Configuring Amazon ECS Linux container instances to receive Spot Instance notices](https://docs.aws.amazon.com/AmazonECS/latest/developerguide/spot-instance-draining-linux-container.html) and [Draining Amazon ECS container instances](https://docs.aws.amazon.com/AmazonECS/latest/developerguide/container-instance-draining.html). You can override this default by setting `ECS_ENABLE_SPOT_INSTANCE_DRAINING=false` in your launch template user data. For more information about launch template user data, see [Use Amazon EC2 launch templates with AWS Batch](launch-templates.md).