Upgrading from an Earlier CDH4 Release
If you are using Cloudera Manager to manage CDH, do not use the instructions on this page. Follow the directions under Upgrading to the Latest Version of CDH4 in a Cloudera Managed Deployment in the Cloudera Manager Installation Guide (or the directions in the Installation Guide for the Cloudera Manager 4.x version you are using) to upgrade to the latest version of CDH4 in a Cloudera-managed deployment.
- Use the right instructions: the following instructions describe how to upgrade to the latest CDH4 release from an earlier CDH4 release. If you are upgrading from a CDH3 release, use the instructions under Upgrading from CDH3 to CDH4 instead.
- MapReduce v1 (MRv1) and MapReduce v2 (YARN): this page covers upgrade for MapReduce v1 (MRv1) and MapReduce v2 (YARN). MRv1 and YARN share common configuration files, so it is safe to configure both of them so long as you run only one set of daemons at any one time. Cloudera does not support running MRv1 and YARN daemons on the same nodes at the same time; it will degrade performance and may result in an unstable cluster deployment. Before deciding to deploy YARN, make sure you read the discussion on the CDH4 Installation page under MapReduce 2.0 (YARN).
When starting, stopping and restarting CDH components, always use the service (8) command rather than running scripts in /etc/init.d directly. This is important because service sets the current working directory to / and removes most environment variables (passing only LANG and TERM) so as to create a predictable environment in which to administer the service. If you run the scripts in/etc/init.d, any environment variables you have set remain in force, and could produce unpredictable results. (If you install CDH from packages, service will be installed as part of the Linux Standard Base (LSB).)
The following sections provide the information and instructions you need: