Enable and configure auto scaling

If your business needs fluctuate, we recommend that you enable auto scaling for your E-MapReduce cluster and configure scaling rules to increase or decrease task nodes based on your business needs.

1. Log on to the Alibaba Cloud E-MapReduce console.
2. In the top navigation bar, select the region where your cluster resides. Select the resource group as required. By default, all resources of the account appear.
3. Click the Cluster Management tab.
4. On the Cluster Management page that appears, find the target cluster and click Details in the Actions column.
5. In the left-side navigation pane of the Cluster Overview page that appears, click Auto Scaling.
6. Click Enable Auto Scaling.
7. On the Auto Scaling Settings page that appears, configure the scaling policy.

   The following table describes the rule types of the scaling policy.

   Type	Description
   Scale By Time	Computing resources are scaled based on time. We recommend that you select this option if your business needs change periodically. For more information, see Configure auto scaling rules by time.
   Spot Instance	A preemptible instance is more cost-effective than a pay-as-you-go instance. However, Alibaba Cloud may release your preemptible instances at any time based on changes in the supply and demand of resources or the market price. For more information, see Create a preemptible instance.

8. After the scaling policy is configured, click Save.
   After auto scaling is configured and triggered, you can view the scaling history and the result of each scaling activity. For more information, see View the scaling history.