> For the complete documentation index, see [llms.txt](https://docs.pentaho.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.pentaho.com/pdc-10.2-data-optimizer/pdso-install-landing-page/pdso-install-in-hadoop-cluster/pdso-install-landing-page-hadoop-installation/installing-data-storage-optimizer-on-apache-ambari-cluster/step-9-restart-data-nodes-in-apache-ambari.md).

# Step 9: Restart data nodes in Apache Ambari

In the Apache Ambari dashboard, perform the following steps:

1. Navigate to the HDFS Summary page.
2. At the top of the page, select either **Restart**, **Restart DataNodes**, or **Service Actions**.
3. Select the configuration settings that are consistent with your normal best practices for data node rolling restarts in this environment.
4. Select **Only restart DataNodes with stale configs**.
5. Select **Trigger Rolling Restart**.

After the rolling restart is complete, the data nodes start tiering to Data Optimizer.

For help verifying that tiering is occurring, see [Tiering HDFS Blocks to Pentaho Data Optimizer](/pdc-10.2-data-optimizer/pdso-install-landing-page/pdso-install-in-hadoop-cluster/pdso-maintain-landing-page/troubleshoot-data-storage-optimizer-fs/tiering-hdfs-blocks-to-pdso.md).


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