Why does chgrp fail in Samba/CIFS mount with Red Hat Storage vfs_glusterfs plugin?

Issue

• chgrp fails in Samba/CIFS mount with Red Hat Storage vfs_glusterfs plugin with following error message:

  chgrp: changing group of <file/directory name>: Permission denied
  

  Logs from RHSS server:

  
  - In  /var/log/samba/glusterfs-<VOLNAME>.%M.log
  
    [2014-06-17 05:27:55.805436] W [client-rpc-fops.c:1983:client3_3_setattr_cbk] 0-testvol-client-0: remote operation 
    failed:  Operation not permitted
  
  - In brick logs
  
     [2014-06-17 05:27:55.805314] E [marker.c:2336:marker_setattr_cbk] 0-testvol-marker: Operation not permitted occurred
     during setattr of <nul>
  
     [2014-06-17 05:27:55.805378] I [server-rpc-fops.c:1788:server_setattr_cbk] 0-testvol-server: 907: SETATTR /test4/4.txt
     (ec8fad40-265d-4761-af8f-562eae9b2bd6) ==> (Operation not permitted)