By default, when AWS CloudFormation encounters a failure during stack creation, it automatically rolls back and deletes any resources that were successfully created. This behavior makes troubleshooting difficult because the failed and partially created resources are no longer available for inspection.

CloudFormation provides the OnFailure parameter to control this behavior. Setting the parameter to DO_NOTHING instructs CloudFormation to stop stack creation when a failure occurs and retain all successfully created resources. This allows the CloudOps engineer to inspect the environment, review logs, and identify the root cause without redeploying resources.

The DisableRollback parameter controls rollback behavior but does not provide the same explicit behavior control during failure scenarios. Rollback triggers are used for monitoring-based rollback, not for preserving resources on failure. Setting OnFailure to ROLLBACK explicitly enforces deletion, which is the opposite of the requirement.

Therefore, setting the OnFailure parameter to DO_NOTHING is the correct solution.