[root@an-node01 ~]# gfs2_edit -p sb /dev/drbd
drbd/         drbd0         drbd1         drbd2         drbd_an1_vg0/ drbd_an2_vg0/ drbd_sh1_vg0/
[root@an-node01 ~]# gfs2_edit -p sb /dev/drbd_sh1_vg0/xen_shared
Block #16    (0x10) of 2443264 (0x254800) (superblock)

Superblock:
  mh_magic              0x01161970(hex)
  mh_type               1                   0x1
  mh_format             100                 0x64
  sb_fs_format          1801                0x709
  sb_multihost_format   1900                0x76c
  sb_bsize              4096                0x1000
  sb_bsize_shift        12                  0xc
  master dir:           2                   0x2
        addr:           22                  0x16
  root dir  :           1                   0x1
        addr:           21                  0x15
  sb_lockproto          lock_dlm
  sb_locktable          an-cluster:xen_shared
  sb_uuid               C85EB2C5-C6C2-D8E6-EDF5-67A5D4581CEE

The superblock has 2 directories
     1. (1). 21 (0x15): Dir     root
     2. (2). 22 (0x16): Dir     master
------------------------------------------------------

[root@an-node01 ~]# /etc/init.d/gfs2 start
Mounting GFS2 filesystems:                                 [  OK  ]

[root@an-node01 ~]# /etc/init.d/gfs2 status
Configured GFS2 mountpoints:
/xen_shared
Active GFS2 mountpoints:
/xen_shared

[root@an-node01 ~]# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/sda2              20G  3.0G   16G  17% /
/dev/sda1             244M   33M  199M  15% /boot
tmpfs                 1.7G     0  1.7G   0% /dev/shm
none                  1.7G   40K  1.7G   1% /var/lib/xenstored
/dev/mapper/drbd_sh1_vg0-xen_shared
                      9.4G  259M  9.1G   3% /xen_shared