This is the documentation for CDH 4.7.1.
Documentation for other versions is available at Cloudera Documentation.

Migrating data between a CDH3 and CDH4 cluster

You can migrate the data from a CDH3 (or any Apache Hadoop) cluster to a CDH4 cluster by using a tool that copies out data in parallel, such as the DistCp tool offered in CDH4. This can be useful if you are not planning to upgrade your CDH3 cluster itself at this point. The following sections provide information and instructions: