High Availability Server

To configure a high availability server, we need to have the following configured:

Hearbeat  -  is a tool which provides cluster infrastructure. It is used to determine if a peer process fails to communicate so that its work can be done by another process.

Pacemaker -  by detecting and recovering from node and service-level failures, it achieves maximum availability for your cluster services.

Apache- or Apache HTTP Server, is an open-source web server application which provides tools for web server development.  It is supported on Linux, Windows and Mac.

In this exercise, the end user should not notice any failure on a particular website even there is really a failure behind the scene. There  will  be  an active and passive server. If the active server fails, the passive server should do  the job instead so that the process will continue.

Here are the steps to solve the problem:

1. First, make sure that the 3 tools are already  installed on your machine. Three computers are required to perform the exercise. Two  computers will be the server and the other one is the client.

2. Edit the Configuration files:

   Suppose our network is 192.168.0.1

for the hosts file,
/etc/hosts   should be

     127.0.0.1 localhost
     192.168.0.5     server1
     192.168.0.6     server2
     192.1168.0.24  cluster

for the authentication keys, 
/etc/ha.d/authkeys     should be

     1 md5 'yourpassword'

other configurations
edit /etc/ha.d/ha.cf
    logfacility local0 
    keepalive 2        
    deadtime 5        
    ping ipaddress   
    udpport 694       
    bcast eth0         
     node server1     
    node server2      
    auto fail_back2  


change the haresources - what will  be accessed by the client ( ipaddress)
edit /etc/ha.d/haresources
       server1 iPaddr::192.168.0.24/24/eth0 apache2

3. Start heartbeat by running:
     /etc/init.d/heartbeat start  or services heartbeat start

Results:

In this exercise, I learned to configure a simple high availability server. I will now think differently everytime I access a website like Facebook. I learned how can server failures be solved using HA server.