Core Upgrade Process

When you upgrade core, you will also upgrade a number of cluster components.

The following cluster components are upgraded with core:

Storage Layer: filesystem fileserver and Container Location Database (CLDB) services
Cluster Management Services: ZooKeeper and Warden
NFS server
Web server, including the Control System user interface and REST API to cluster services
The maprcli commands for managing cluster services
Any new features and performance enhancements introduced with the new version.

When you upgrade core, the following changes occur within the /opt/mapr directory:

If required, additional folders are added.
Product binaries are replaced by binaries associated with the new version.

Existing configuration files remain in the active directory and default configuration files associated with the new version are installed in a new directory:

Default Configuration File Directories	Active Configuration File Directories
`/opt/mapr/conf.new`	`/opt/mapr/conf`
`/opt/mapr/conf/conf.d.new`	`/opt/mapr/conf/conf.d`

When core includes an updated hadoop common version, a new hadoop directory is installed and the following changes also occur:

The /opt/mapr/conf/hadoop_version file reflects the new hadoop version number.
Paths in the /opt/mapr/conf/conf.d/warden.<servicename>.conf files reflect the new hadoop directory.
The following symlinks in /opt/mapr/lib reflect the new hadoop version:
- hadoop-auth-2.x.x.jar
- hadoop-yarn-api-2.x.x.jar
- hadoop-yarn-client-2.x.x.jar
- hadoop-yarn-common-2.x.x.jar
- hadoop-common-2.x.x.jar
A new hadoop 2.x directory is created under /opt/mapr/hadoop.

If a hadoop 2.x directory already exists, the configuration files from the existing hadoop 2.x directory will replace the default configuration files in the new 2.x hadoop directory thereby retaining the existing configuration. The existing hadoop 2.x directory is also moved into the following directory: /opt/mapr/hadoop/OLD_HADOOP_VERSION.