This is documentation for MapR Version 5.0. You can also refer to MapR documentation for the latest release.

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The YARN Log Aggregation option aggregates and moves log files for completed applications from the local file system to the MapR-FS.  This This allows users to view the entire set of logs for a particular application using the HistoryServer UI or by running the yarn logs command. 


Then restart the Node Manager services. This setting enables impersonation for Node Manager processes so that log files can be created with the correct user ownership. 

Aggregated logs are owned by the user who runs the job. For example, when user admin runs a job, the logs are stored to maprfs:///tmp/logs/admin. If user analyst runs a job, the logs are stored to maprfs:///tmp/logs/analyst. If these two users do not share the same UNIX group, they will not be able to see each other's logs.

If centralized logging and YARN log aggregation are enabled, the logs for MapReduce v2 applications will be managed by Centralized Logging while the logs for non-MapReduce applications will be managed by YARN log aggregation.