MapR Hadoop features the complete Hadoop distribution including components such as Hive and HBase. There are a few things to know about migrating Hive and HBase, or about migrating custom components you have patched yourself.
If you have applied your own patches to a component and wish to continue to use that customized component with the MapR distribution, you should keep the following considerations in mind:
- MapR libraries: All Hadoop components must point to MapR for the Hadoop
libraries. Change any absolute paths. Do not hardcode
maprfs://into your applications. This is also true of Hadoop ecosystem components that are not included in the MapR Hadoop distribution (such as Cascading). For more information see Working with MapR-FS.
- Component compatibility: Before you commit to the migration of a customized component (for example, customized HBase), check the MapR release notes to see if MapR Technologies has issued a patch that satisfies your business requirements. MapR Technologies publishes a list of Hadoop common patches and MapR patches with each release and makes those patches available for our customers to take, build, and deploy.
- ZooKeeper coordination service: Certain components, such as HBase, depend on ZooKeeper. When you migrate your customized component from the HDFS cluster to the MapR cluster, make sure it points correctly to the MapR ZooKeeper service.