This is solved with the forthcoming ACL patch, which is confirmed to work on MR2, and , with a minor update, also works on MR1 for hadoop >1.2 (and probable/possibly hadoop < 1.2, although not yet tested). The solution is detailed here : https://forge.gluster.org/hadoop/pages/Security
Per 11/13 bug triage meeting, re-assigning to bchilds.
quick note that this is essentially a duplicate of 970183: running with multiple users. Closing.
*** This bug has been marked as a duplicate of bug 970183 ***