Thanks for your reply.
I didn't use GFS2, but I use NFS to store live-backup's messaging journals.
and I mount NFS on the directory - /home/user/jboss-as-7.0.1.Final/standalone/data
I'm sure that both live and backup servers can access this nfs directory.
I know using SAN-like shared file system is better, but I don't care the problem of efficiency now.
Does the difference of NFS and GFS2 may cause this kind of problem?