Presently MapReduce will not work if the JobTracker is run under a user other than root due to the fact that the glusterfs plugin for Hadoop calls getfattr (via getFileBlockLocations) which requires superuser privileges.
GA Workaround: Job and Task trackers may run as any non root user, as long as its identical on all systems. The UIDs must also match. The mapreduce job must also be submitted as the same user/UID. In addition, each system must have a sudoers entry allowing sudo access to the getfattr command by the user that started the trackers and is submitting the job. An example of the correct sudoers setup is creating a file /etc/sudoers.d/gluster, and add the line: mapred ALL= NOPASSWD: /usr/bin/getfattr where mapred is replaced by the user running the trackers + job.