maximumPercent

If a service is using the rolling update (`ECS`) deployment type, the `maximumPercent` parameter represents an upper limit on the number of your service's tasks that are allowed in the `RUNNING` or `PENDING` state during a deployment, as a percentage of the `desiredCount` (rounded down to the nearest integer). This parameter enables you to define the deployment batch size. For example, if your service is using the `REPLICA` service scheduler and has a `desiredCount` of four tasks and a `maximumPercent` value of 200%, the scheduler may start four new tasks before stopping the four older tasks (provided that the cluster resources required to do this are available). The default `maximumPercent` value for a service using the `REPLICA` service scheduler is 200%. If a service is using either the blue/green (`CODE_DEPLOY`) or `EXTERNAL` deployment types, and tasks in the service use the EC2 launch type, the maximum percent value is set to the default value. The maximum percent value is used to define the upper limit on the number of the tasks in the service that remain in the `RUNNING` state while the container instances are in the `DRAINING` state. You can't specify a custom `maximumPercent` value for a service that uses either the blue/green (`CODE_DEPLOY`) or `EXTERNAL` deployment types and has tasks that use the EC2 launch type. If the tasks in the service use the Fargate launch type, the maximum percent value is not used, although it is returned when describing your service.