Why does gluster NFS server fail to start in RHGS 3.1

Issue

• Could not access gluster volume over NFS
• The gluster volume status showing the NFS process is not available.

[root@rhgsnode ~]# gluster vol status
Status of volume: gvol-nfs
Gluster process                             TCP Port  RDMA Port  Online  Pid
------------------------------------------------------------------------------
Brick rhgsnode01:/volbricks/b2/ag
ty-nfs                                      49153     0          Y       990
Brick rhgsnode02:/volbricks/b2/ag
ty-nfs                                      49153     0          Y       16762
NFS Server on localhost                     N/A       N/A        N       N/A        <<========================
Self-heal Daemon on localhost               N/A       N/A        Y       16799
NFS Server on 10.0.0.24                  N/A       N/A        N       N/A
Self-heal Daemon on 10.0.0.24            N/A       N/A        Y       1024

• The showmount command fail for gluster volume nfs export

# showmount -e
clnt_create: RPC: Program not registered