After the volume is tagged using group virt command, you must not use the volume for any other storage purpose, other than to store virtual machine images. Also, ensure to access the volume only through gluster native client.
Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory, and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. http://rhn.redhat.com/errata/RHBA-2013-1262.html