* https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html-single/high_availability_add-on_administration/index
  * https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html-single/global_file_system_2/index
  * https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/global_file_system_2/ch-clustsetup-gfs2
  * https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html-single/high_availability_add-on_reference/index
  * https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html-single/global_file_system_2/index
  * This is just intended for simple experiments
<code>
# deploy 2 guests, rhel7u5

# following to be done on both nodes
cat >/etc/yum.repos.d/base.repo <<EOT
[rhel-7.5]
name=rhel-7.5
baseurl=http://192.168.4.1/repos/rhel-7.5

[rhel-7.5ha]
name=rhel-7.5ha
baseurl=http://192.168.4.1/repos/rhel-7.5/addons/HighAvailability/

[rhel-7.5res]
name=rhel-7.5res
baseurl=http://192.168.4.1/repos/rhel-7.5/addons/ResilientStorage/
EOT

yum groupinstall -y ha
yum install -y lvm2-cluster gfs2-utils
systemctl enable --now pcsd.service

echo -n redhat | passwd hacluster --stdin

# to be done on one node
pcs cluster auth rhel7u5a.local rhel7u5b.local
pcs cluster setup --start --name my_cluster rhel7u5a.local rhel7u5b.local
# pcs property set stonith-enabled=false
pcs cluster enable --all
pcs cluster status

### fencing
# setup hypervisor as per https://access.redhat.com/solutions/55920
pcs stonith list
pcs stonith describe [..]

[root@rhel7u5a ~]# fence_xvm -o list
fed                              e9ba894d-ae8e-41dd-ad56-c10dcdbf0741 off
master                           cb678f0c-8817-4ecd-9d16-c814e8749daa off
rhel4u8                          ccc352a1-5bfb-4bf4-9473-3f5cedd65599 off
rhel5u11                         9e720e71-b583-4ef9-86f1-c00d7f36e07f off

pcs stonith create xvmfence  fence_xvm key_file=/etc/cluster/fence_xvm.key
pcs stonith # status

# shared disk, iscsi from hypervisor
# ensure /etc/iscsi/initiatorname.iscsi on your nodes is different!
md5sum /etc/iscsi/initi*
systemctl enable --now iscsi
iscsiadm --mode discovery --type sendtargets --portal 192.168.4.16
iscsiadm -m node --target iqn.2003-01.org.x:disk1 -p 192.168.4.16 -l

# setup gfs2
pcs property set no-quorum-policy=freeze
pcs resource create dlm ocf:pacemaker:controld op monitor \
  interval=30s on-fail=fence clone interleave=true ordered=true

mkfs.gfs2 -p lock_dlm -j 2 -t my_cluster:data1 /dev/sda
mount /dev/sda /mnt
</code>