How To Configure Online Failover/Failback on CentOS 6 Using Heartbeat
Heartbeat is a daemon that provides cluster infrastructure (communication and membership) services to its clients. This allows clients to know about the presence (or disappearance!) of peer processes on other machines and to easily exchange messages with them.
In this guidance, i am build 2 system for online failover. The systems using CentOS 6 64 Bit. For easy understanding, this is my information system
# Configure Network
First, we must configure network on CentOS. Assuming name of your network interface is eth0. Do the following configuration on all nodes (node1 and node2) and adjust on node2
Restart network service and setup for automatic boot on all nodes (node1 and node2)
# Configure Disable Selinux & Firewall on all nodes (node1 and node2)
Open file /etc/sysconfig/selinux and change SELINUX=enforcing become SELINUX=disabled.
Also disable some service such as iptables and ip6tables.
# Configure /etc/hosts and hostname on all nodes (node1 and node2)
Open file /etc/hosts and configure as follows
Do the following command as root and open file /etc/sysconfig/network to change hostname
– On node1
Change HOSTNAME so that like below :
– On node2
Change HOSTNAME so that like below :
# Update repos and install packages Heartbeat on all nodes (node1 and node2)
If you cannot get epel repo, please use this repo and install : http://dl.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm
# Configure Heartbeat
– Create a file /etc/ha.d/ha.cf (enough on node1 only)
fill with the following line
Note :
eth0 is interface on your system. If your system using eth1 for interface name, please change eth0 to the eth1. 192.168.80.92 is IP Address of node2
– Create a file /etc/ha.d/authkeys (enough on node1 only)
fill with the following line
change permission authkeys
– Create a file /etc/ha.d/haresources (enough on node1 only)
fill with the following line
Note :
node1.imanudin.net will become as a master server. 192.168.80.93 is an alias IP for testing online/failover
# Copy those files from node1 to node2 (run the following command on node1)
# Change ha.cf file on node2 (run the following command on node2)
change line ucast eth0 192.168.80.92 so that become
# Start service Heartbeat and configure for automatic startup at boot on all nodes (node1 and node2)
TESTING ONLINE FAILOVER/FAILBACK
After your start service heartbeat on all nodes, you will see an alias IP on node1. Please check with command ifconfig. For testing failover, please stop service heartbeat on node1 (service heartbeat stop). Please check your IP on node2 with command ifconfig. You will see an alias IP on node2 (an alias IP that has been taken by node2). For testing failback, please start again service heartbeat on node1 (service heartbeat start). An alias IP will automatically taken by node1.
TESTING WITH APACHE WEB SERVER
Please install Apache on all nodes
– Create an index.html on DocumentRoot node1
Fill with the following example
Please try to access node1 via browser. You will see a text This is node1
– Create an index.html on DocumentRoot node2
Fill with the following example
Please try to access node2 via browser. You will see a text This is node2
Integrate Apache with Heartbeat
Please change file /etc/ha.d/haresources on all nodes
so that like below :
Please try to access an alias IP from browser. You will see a text This is node1. Please try to stop Heartbeat service on node1 and refresh browser. You will see a text This is node2
(all services handled by Heartbeat on node1 will be taken by node2).
For failback, please start again Heartbeat service on node1 (all
services handled by Heartbeat on node2 will be taken again by node1)
You could also experiment with other services for online failover such as Samba, MySQL, MariaDB etc. The Heartbeat application only configure failover/failback, not data synchronize.
Good luck and hopefully useful
Heartbeat is a daemon that provides cluster infrastructure (communication and membership) services to its clients. This allows clients to know about the presence (or disappearance!) of peer processes on other machines and to easily exchange messages with them.
In this guidance, i am build 2 system for online failover. The systems using CentOS 6 64 Bit. For easy understanding, this is my information system
# Server 1 Hostname : node1 Domain : imanudin.net IP Address : 192.168.80.91 # Server 2 Hostname : node2 Domain : imanudin.net IP Address : 192.168.80.92 # Alias IP for online failover testing IP Address : 192.168.80.93
# Configure Network
First, we must configure network on CentOS. Assuming name of your network interface is eth0. Do the following configuration on all nodes (node1 and node2) and adjust on node2
1.vi /etc/sysconfig/network-scripts/ifcfg-eth0DEVICE=eth0 ONBOOT=yes NM_CONTROLLED=no BOOTPROTO=none IPADDR=192.168.80.91 NETMASK=255.255.255.0 DNS1=192.168.80.91 GATEWAY=192.168.80.11 DNS2=192.168.80.11 DNS3=8.8.8.8 USERCTL=no
Restart network service and setup for automatic boot on all nodes (node1 and node2)
1.service network restart2.chkconfig network on# Configure Disable Selinux & Firewall on all nodes (node1 and node2)
Open file /etc/sysconfig/selinux and change SELINUX=enforcing become SELINUX=disabled.
Also disable some service such as iptables and ip6tables.
1.setenforce 02.service iptables stop3.service ip6tables stop4.chkconfig iptables off5.chkconfig ip6tables off# Configure /etc/hosts and hostname on all nodes (node1 and node2)
Open file /etc/hosts and configure as follows
# node1 127.0.0.1 localhost 192.168.80.91 node1.imanudin.net node1 192.168.80.92 node2.imanudin.net node2 # node2 127.0.0.1 localhost 192.168.80.91 node1.imanudin.net node1 192.168.80.92 node2.imanudin.net node2
Do the following command as root and open file /etc/sysconfig/network to change hostname
– On node1
1.hostname node1.imanudin.net2.vi /etc/sysconfig/networkChange HOSTNAME so that like below :
NETWORKING=yes HOSTNAME=node1.imanudin.net
– On node2
1.hostname node2.imanudin.net2.vi /etc/sysconfig/networkChange HOSTNAME so that like below :
NETWORKING=yes HOSTNAME=node2.imanudin.net
# Update repos and install packages Heartbeat on all nodes (node1 and node2)
1.yum update2.yum install epel-release3.yum -y install heartbeatIf you cannot get epel repo, please use this repo and install : http://dl.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm
# Configure Heartbeat
– Create a file /etc/ha.d/ha.cf (enough on node1 only)
1.vi /etc/ha.d/ha.cffill with the following line
keepalive 2 warntime 5 deadtime 15 initdead 90 udpport 694 auto_failback on ucast eth0 192.168.80.92 logfile /var/log/ha-log node node1.imanudin.net node2.imanudin.net
Note :
eth0 is interface on your system. If your system using eth1 for interface name, please change eth0 to the eth1. 192.168.80.92 is IP Address of node2
– Create a file /etc/ha.d/authkeys (enough on node1 only)
1.vi /etc/ha.d/authkeysauth 2 2 crc
change permission authkeys
1.chmod 0600 /etc/ha.d/authkeys1.vi /etc/ha.d/haresourcesnode1.imanudin.net IPaddr::192.168.80.93/24/eth0:0
Note :
node1.imanudin.net will become as a master server. 192.168.80.93 is an alias IP for testing online/failover
# Copy those files from node1 to node2 (run the following command on node1)
1.cd /etc/ha.d/2.scp authkeys ha.cf haresources root@192.168.80.92:/etc/ha.d/1.vi /etc/ha.d/ha.cfucast eth0 192.168.80.91192.168.80.91 is IP Address of node1
# Start service Heartbeat and configure for automatic startup at boot on all nodes (node1 and node2)
1.service heartbeat start2.chkconfig heartbeat onAfter your start service heartbeat on all nodes, you will see an alias IP on node1. Please check with command ifconfig. For testing failover, please stop service heartbeat on node1 (service heartbeat stop). Please check your IP on node2 with command ifconfig. You will see an alias IP on node2 (an alias IP that has been taken by node2). For testing failback, please start again service heartbeat on node1 (service heartbeat start). An alias IP will automatically taken by node1.
TESTING WITH APACHE WEB SERVER
Please install Apache on all nodes
1.yum install httpd1.vi /var/www/html/index.htmlThis is node1Save and restart service Apache
1.service httpd restart– Create an index.html on DocumentRoot node2
1.vi /var/www/html/index.htmlThis is node2Save and restart service Apache
1.service httpd restartIntegrate Apache with Heartbeat
Please change file /etc/ha.d/haresources on all nodes
1.vi /etc/ha.d/haresourcesnode1.imanudin.net IPaddr::192.168.80.93/24/eth0:0 httpdStop service Apache and configure automatic off at boot on all nodes (Service Apache will be handled by Heartbeat)
1.service httpd stop2.chkconfig httpd offYou could also experiment with other services for online failover such as Samba, MySQL, MariaDB etc. The Heartbeat application only configure failover/failback, not data synchronize.
Good luck and hopefully useful
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