14 Further Testing

You can now access the web site that is hosted by the two Apache nodes by typing http://192.168.0.105 in your browser.

Now stop the Apache on either webserver1 or webserver2. You should then still see the web site on http://192.168.0.105 because the load balancer directs requests to the working Apache node. Of course, if you stop both Apaches, then your request will fail.

Now let's assume that loadb1 is our active load balancer, and loadb2 is the hot-standby. Now stop heartbeat on loadb1:

loadb1:

/etc/init.d/heartbeat stop

Wait a few seconds, and then try http://192.168.0.105 again in your browser. You should still see your web site because loadb2 has taken the active role now.

Now start heartbeat again on loadb1:

loadb1:

/etc/init.d/heartbeat start

loadb2 should still have the active role. Do the tests from chapter 5 again on loadb1 and loadb2, and you should see the inverse results as before.

If you have also passed these tests, then your loadbalanced Apache cluster is working as expected. Have fun!

15 Further Reading

This tutorial shows how to loadbalance two Apache nodes. It does not show how to keep the files in the Apache document root in sync or how to create a storage solution like an NFS server that both Apache nodes can use, nor does it provide a solution how to manage your MySQL database(s). You can find solutions for these issues here:

• Mirror Your Web Site With rsync
• Setting Up A Highly Available NFS Server
• How To Set Up A Load-Balanced MySQL Cluster
• How To Set Up Database Replication In MySQL

16 Links

• heartbeat / The High-Availability Linux Project: http://linux-ha.org
• The Linux Virtual Server Project: http://www.linuxvirtualserver.org
• Ultra Monkey: http://www.ultramonkey.org

17 References and Sources

• Falko's Article "The Perfect Server - Ubuntu Hardy Heron (Ubuntu 8.04 LTS Server)"
• Falko's Article "How to Set up A Loadbalanced High-Availability Apache Cluster"
• BIND on Ubuntu "Howto: Setup a DNS server with bind"