How to configure High Availability Linux Cluster with Pacemaker in CentOS

After the installation, set password for the " hacluster" on both nodes. Verify the user account by running the following command.

[root@linuxhelp1 ~]# tail /etc/passwd 
abrt:x:173:173::/etc/abrt:/sbin/nologin
pulse:x:171:171:PulseAudio System Daemon:/var/run/pulse:/sbin/nologin
gdm:x:42:42::/var/lib/gdm:/sbin/nologin
gnome-initial-setup:x:993:991::/run/gnome-initial-setup/:/sbin/nologin
postfix:x:89:89::/var/spool/postfix:/sbin/nologin
sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin
tcpdump:x:72:72::/:/sbin/nologin
user1:x:1000:1000:user1:/home/user1:/bin/bash
apache:x:48:48:Apache:/usr/share/httpd:/sbin/nologin
hacluster:x:189:189:cluster user:/home/hacluster:/sbin/nologin

And then run the following command to set the password for the “ hacluster” account.

[root@linuxhelp1 ~]# passwd hacluster 
Changing password for user hacluster.
New password:
Retype new password:
passwd: all authentication tokens updated successfully.

Start and enable the service for pacemaker on both the nodes.

[root@linuxhelp1 ~]# systemctl start pcsd
[root@linuxhelp1 ~]# systemctl enable pcsd 
ln -s ' /usr/lib/systemd/system/pcsd.service'  ' /etc/systemd/system/multi-user.target.wants/pcsd.service' 

To create cluster

Before creating clusters authenticate the nodes that is to be added by using the following command.

[root@linuxhelp1 ~]# pcs cluster auth linuxhelp1 linuxhelp2 -u hacluster 
Password:
linuxhelp2: Authorized
linuxhelp1: Authorized

Then utilize the below command to create the Cluster and then add the authenticated nodes into it.

[root@linuxhelp1 ~]# pcs cluster setup --name Cluster linuxhelp1 linuxhelp2 
Shutting down pacemaker/corosync services...
Redirecting to /bin/systemctl stop pacemaker.service
Redirecting to /bin/systemctl stop corosync.service
Killing any remaining services...
Removing all cluster configuration files...
linuxhelp1: Succeeded
linuxhelp2: Succeeded
Synchronizing pcsd certificates on nodes linuxhelp1, linuxhelp2...
linuxhelp2: Success
linuxhelp1: Success

Restaring pcsd on the nodes in order to reload the certificates...
linuxhelp2: Success
linuxhelp1: Success

After the cluster creation, make sure that the nodes added into it by verifying the configuration file.

[root@linuxhelp1 ~]# cat /etc/corosync/corosync.conf 
totem {
version: 2
secauth: off
cluster_name: Cluster
transport: udpu
}

nodelist {
node {
ring0_addr: linuxhelp1
nodeid: 1
}

node {
ring0_addr: linuxhelp2
nodeid: 2
}
}

quorum {
provider: corosync_votequorum
two_node: 1
}

logging {
to_logfile: yes
logfile: /var/log/cluster/corosync.log
to_syslog: yes
}

Run the following command to start the cluster services.

[root@linuxhelp1 ~]# pcs cluster start --all 
linuxhelp2: Starting Cluster...
linuxhelp1: Starting Cluster...
[root@linuxhelp1 ~]# pcs status
Cluster name: Cluster
WARNING: no stonith devices and stonith-enabled is not false
Last updated: Wed Sep 14 16:30:06 2016 Last change: Wed Sep 14 16:29:52 2016 by hacluster via crmd on linuxhelp2
Stack: unknown
Current DC: NONE
2 nodes and 0 resources configured

Node linuxhelp1: UNCLEAN (offline)
Node linuxhelp2: UNCLEAN (offline)

Full list of resources:

PCSD Status:
linuxhelp1: Online
linuxhelp2: Online

Daemon Status:
corosync: active/disabled
pacemaker: active/disabled
pcsd: active/enabled

Enable the cluster services by running the following command.

[root@linuxhelp1 ~]# pcs cluster enable --all 
linuxhelp1: Cluster Enabled
linuxhelp2: Cluster Enabled

To add resource into the cluster

Next, lets start to append the resources into the cluster. Here we are going to add two resources namely web server(httpd) and IP address(Virtual IP). These resources are added to the cluster to make the services available without any downtime.

[root@linuxhelp1 ~]# pcs resource create VirtIP IPAddr ip=192.168.5.150 cidr_netmask=24 op monitor interval=30s
[root@linuxhelp1 ~]# pcs resource create Httpd apache configuration=" /etc/httpd/conf/httpd.conf"  op monitor interval=30s 

Run the following command to check the status of the cluster.

[root@linuxhelp1 ~]# pcs status 
Cluster name: Cluster
WARNING: no stonith devices and stonith-enabled is not false
Last updated: Wed Sep 14 17:13:47 2016 Last change: Wed Sep 14 17:11:54 2016 by root via cibadmin on linuxhelp1
Stack: corosync
Current DC: linuxhelp1 (version 1.1.13-10.el7_2.4-44eb2dd) - partition with quorum
2 nodes and 2 resources configured

Online: [ linuxhelp1 linuxhelp2 ]

Full list of resources:

VirtIP (ocf::heartbeat:IPaddr): Stopped
Httpd (ocf::heartbeat:apache): Stopped

PCSD Status:
linuxhelp1: Online
linuxhelp2: Online

Daemon Status:
corosync: active/enabled
pacemaker: active/enabled
pcsd: active/enabled
Check the status of the resources alone.

[root@linuxhelp1 ~]# pcs status resources 
VirtIP (ocf::heartbeat:IPaddr): Stopped
Httpd (ocf::heartbeat:apache): Stopped
After creating the resources, start the services by running the following command.

[root@linuxhelp1 ~]# pcs constraint colocation add Httpd with VirtIP INFINITY 
Then assign the following values into the cluster.

[root@linuxhelp1 ~]# pcs property set stonith-enabled=false
[root@linuxhelp1 ~]# pcs property set no-quorum-policy=ignore
[root@linuxhelp1 ~]# pcs property set default-resource-stickiness=" INFINITY"  
Run the following command to check the status of the resources and clusters.

[root@linuxhelp1 ~]# pcs status resources 
VirtIP (ocf::heartbeat:IPaddr): Started linuxhelp1
Httpd (ocf::heartbeat:apache): Started linuxhelp1
[root@linuxhelp1 ~]# pcs status 
Cluster name: Cluster
Last updated: Wed Sep 14 17:52:55 2016 Last change: Wed Sep 14 17:40:24 2016 by root via cibadmin on linuxhelp1
Stack: corosync
Current DC: linuxhelp1 (version 1.1.13-10.el7_2.4-44eb2dd) - partition with quorum
2 nodes and 2 resources configured

Online: [ linuxhelp1 linuxhelp2 ]

Full list of resources:

VirtIP (ocf::heartbeat:IPaddr): Started linuxhelp1
Httpd (ocf::heartbeat:apache): Started linuxhelp1

PCSD Status:
linuxhelp1: Online
linuxhelp2: Online

Daemon Status:
corosync: active/enabled
pacemaker: active/enabled
pcsd: active/enabled

To check the Fail over

After configuring the cluster, check the Fail over between the nodes. Create different index files on the node1 and node2 with different content as shown below.

[root@linuxhelp1 ~]# vim /var/www/html/index.html 

Entry:

This is Node1
[root@linuxhelp1 ~]# vim /var/www/html/index.html 

Entry:

This is Node2

Trigger the browser with the following link http://< IP_ADDR>

Stop the cluster service for node 1.

[root@linuxhelp1 ~]# pcs cluster stop linuxhelp1 
linuxhelp1: Stopping Cluster (pacemaker)...
linuxhelp1: Stopping Cluster (corosync)...