# verify /dev/sdc is accessable by all nodes
mkqdisk -l newclus -c /dev/sdc     # replace newclus (labelname) with the clustername
cp /etc/cluster/cluster.conf cp /etc/cluster/cluster.conf_preqdisk
vi /etc/cluster/cluster.conf
# increase config_version
# add:
#  <quorumd interval="1" device="/dev/sdc" tko="8" votes="1" log_level="7" label="newclus"/>
# change i.e. 
#  <cman expected_votes="1" two_node="1"/>
# into
#  <cman expected_votes="3" two_node="0"/>

# distribute new config
ccs_tool update cluster.conf

# activate service
service qdiskd start
chkconfig qdiskd on

# check the qdisk appears now
cluststat