===== Pacemaker with GFS2 RHEL 7 =====

==== Install and initial cluster configuration ====

/etc/hosts configuration example on both nodes:
<code>
    192.168.122.10        cluster-1.exmaple.com    cluster-1
    192.168.122.15        cluster-2.example.com    cluster-2
</code>

Yum configuration on both nodes:
<code>
[cdrom]
name=cdrom
baseurl=file:///media
gpgcheck=0
enabled=1

[ha]
name=ha
baseurl=file:///media/addons/HighAvailability/
gpgcheck=0
enabled=1

[storage]
name=storage
baseurl=file:///media/addons/ResilientStorage/
gpgcheck=0
enabled=1
</code>

On both nodes:
<code>
sudo yum install pcs pacemaker fence-agents-all sbd lvm2-cluster gfs2-utils
sudo systemctl disable firewalld
sudo systemctl stop firewalld
echo 'manager' |sudo passwd hacluster --stdin
sudo systemctl start pcsd.service
sudo systemctl enable pcsd.service
</code>

On one node:
<code>
sudo pcs cluster auth -u hacluster ha1.gbmdc.dc ha2.gbmdc.dc
sudo pcs cluster setup --start --name spyderdb ha1.gbmdc.dc ha2.gbmdc.dc
sudo pcs cluster enable --all
</code>

==== Configure fencing ====

Edit /etc/modules-load.d/softdog.conf on both nodes:
<code>
softdog
</code>

Execute:
<code>
sudo systemctl enable systemd-modules-load
sudo systemctl start systemd-modules-load
sudo pcs stonith sbd device setup --device=/dev/sdb
sudo pcs cluster stop --all
sudo pcs stonith sbd enable
sudo pcs cluster start --all
sudo pcs property set stonith-watchdog-timeout=10
sudo pcs stonith create sbd fence_sbd devices=/dev/sdb
</code>
Edit /etc/sysconfig/sbd on both nodes:
<code>
SBD_DEVICE="/dev/sdb"
</code>

Reboot nodes. After check if the output of this command is correct:
<code>
ps aux | grep -e COMMAND -e "sbd: watcher: /dev" | grep -v grep
</code>
==== Configure File system ====
<code>
sudo pcs property set no-quorum-policy=freeze
sudo pcs resource create dlm ocf:pacemaker:controld op monitor interval=30s on-fail=fence
</code>
On both nodes:
<code>
sudo /sbin/lvmconf --enable-cluster
sudo mkdir /spyderha
</code>
On one node:
<code>
sudo pcs resource create clvmd ocf:heartbeat:clvm op monitor interval=30s on-fail=fence
sudo pcs constraint order start dlm then clvmd
sudo pcs constraint colocation add clvmd with dlm
sudo pvcreate /dev/sda
sudo vgcreate -Ay -cy spyderDB_VG /dev/sda
sudo lvcreate -L10G -n spyderDB_LV spyderDB_VG
sudo mkfs.ext4 /dev/mapper/spyderDB_VG-spyderDB_LV
sudo pcs resource create clusterfs Filesystem device="/dev/mapper/spyderDB_VG-spyderDB_LV" directory="/spyderha" fstype="ext4"
sudo pcs constraint order start clvmd then clusterfs
sudo pcs constraint colocation add clusterfs with clvmd
sudo pcs resource group add spyderdb dlm clvmd hafs VirtualIP
</code>

==== Problems ====
<code>
Skipping clustered volume group spyderDB_VG
vgchange -cn $vgname --config 'global {locking_type = 0}'
</code>

==== Resource HTTPd example ====
Edit /etc/sysconfig/selinux:
<code>
SELINUX=permissive
</code>
On both nodes:
<code>
sudo setenforce 0
sudo yum -y install httpd
sudo sed -i 's/\/var\/www/\/spyderha/g' /etc/httpd/conf/httpd.conf
</code>
On one node:
<code>
sudo mkdir /spyderha/cgi-bin
sudo mkdir /spyderha/html
sudo pcs resource defaults resource-stickiness=15000
sudo pcs resource create httpd systemd:httpd --group spyderdb
sudo pcs resource create VirtualIP IPaddr2 ip=192.168.122.20 cidr_netmask=24 --group spyderdb
sudo pcs constraint order clusterfs-clone then httpd
</code>

==== Disable monitoring of resources ====
<code>
pcs resource update httpd op monitor enabled=false
</code>

==== Monitor but do nothing ====
<code>
pcs resource update httpd op monitor on-fail=block
</code>

==== References ====
  * https://access.redhat.com/solutions/1609883
  * http://www.linux-ha.org/wiki/SBD_Fencing
  * https://access.redhat.com/articles/3099231
  * https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/global_file_system_2/ch-clustsetup-gfs2
  * https://www.suse.com/documentation/sle-ha-12/book_sleha/data/sec_ha_storage_protect_fencing_setup.html#pro_ha_storage_protect_sbd_create
  * https://access.redhat.com/articles/2943361
  * https://docs.oracle.com/cd/E52668_01/E54669/html/ol7-pacemaker-stonith.html