GFS on iSCSI shared storage

This method, based on software version delivered with CentOS 6.0 use dlm_controld.pcmk and gfs_controld.pcmk, which are special version developped to be used directly by Pacemaker. After upgrading the OS to CentOS 6.2, the RPM providing dlm_controld.pcmk and gfs_controld.pcmk were replaced by cman, wichi provides the standard gfs_controld and dlm_controld. To be use these two with Pacemaker, we need to enable CMAN with Corosync.