Rolling Back a CDH 4-to-CDH 5 Upgrade
You can roll back an upgrade from CDH 4 to CDH 5. The rollback restores your CDH cluster to the state it was in before the upgrade, including Kerberos and TLS/SSL configurations. Any data created after the upgrade is lost.
In a typical upgrade, you first upgrade Cloudera Manager from version 4.x to version 5.x, and then you use the upgraded version of Cloudera Manager 5 to upgrade CDH 4 to CDH 5. (See Upgrading CDH and Managed Services Using Cloudera Manager.) If you want to roll back this upgrade, follow these steps to roll back your cluster to its state prior to the upgrade.
- Before the upgrade, back up specified directories, files, and databases used in your CDH cluster.
- To roll back your cluster to its state before the upgrade, perform the rollback steps on the hosts in your CDH cluster.
- Use Cloudera Manager 5 to start and manage the CDH 4 cluster. You can use Cloudera Manager 5 to manage both CDH 4 and CDH 5 clusters. (If required, you can also roll back Cloudera Manager 5 to Cloudera Manager 4.)
- If you have finalized the HDFS upgrade, you cannot roll back your cluster.
- Configuration changes, including the addition of new services or roles after the upgrade, are not retained after rolling back Cloudera Manager.
- Cloudera recommends that you not make configuration changes or add new services and roles until you have finalized the HDFS upgrade and no longer require the option to roll back your upgrade.
- If your cluster is configured to use HBase replication, data written to HBase after the upgrade might not be replicated to peers when you start your rollback. This topic does not describe how to determine which, if any, peers have the replicated data and how to roll back that data. For more information about HBase replication, see HBase Replication.