When a large amount of compute resources remains idle in your E-MapReduce (EMR) cluster, you can reduce the number of task nodes in the cluster. This topic describes how to scale in a cluster.


A cluster is created on the EMR on ECS page. For more information, see Create a cluster.


  • You can reduce only the number of task nodes to scale in an EMR cluster. The cluster that you want to scale in must meet the following requirements:
    • The EMR version of the cluster is V5.X later than V5.6.0 or V3.X later than V3.2.0.
    • The cluster is in the Running state.
    • The billing method of the task node group is Pay-As-You-Go or Preemptible Instance.
    Note If you want to reduce the number of core nodes or subscription task nodes to scale in a cluster, follow the instructions described in Scale in a node group.
  • For Hadoop clusters, you cannot scale out a node group that is created on the Auto Scaling tab. For more information, see Configure auto scaling (only for Hadoop clusters).


  1. Go to the Nodes tab.
    1. Log on to the EMR console. In the left-side navigation pane, click EMR on ECS.
    2. In the top navigation bar, select the region where your cluster resides and select a resource group based on your business requirements.
    3. On the EMR on ECS page, find the cluster that you want to scale out and click Nodes in the Actions column.
  2. On the Nodes tab, click Scale In in the Actions column of the node group that you want to scale in.
  3. In the Scale In dialog box, click the downward arrow for Reserved Nodes or enter a number in this field to reduce the number of task nodes.
  4. After you complete the configuration, click OK.