Clustered cPanel

Dear fellow cPanel system administrators,

After a few months of testing I can finally say that I have successfully clustered cPanel.

The setup includes two load-balancers and two web-hosting nodes. The load-balancers act as shared storage for the web-hosting nodes as well, although a SAN can be used as shared storage as well.

I am using HAproxy as the incoming HTTP/HTTPS/FTP/MAIL load-balancer software. The shared storage filesystem is OCFS2 (Orace Cluster Filsystem).
To ensure high-availability on the load-balancer frontend, I am using DRBD to replicate the block device over network, to the second load-balancer node. The load-balancer setup is in a active/passive failover mode.
If the active load-balancer fails, the passive load-balancer will automatically take over, without the need for any manual intervention.

cPanel is configured to use remote MySQL, which is located on the load-balancer.

The two web hosting cPanel nodes uses the shared storage from the load-balancer, to store the users home directories on, as well as the cpanel configuration files.

The WHM panel is load-balanced as well.
All this is done without any hacking to the cPanel code.

I am using XEN as the virtualization infrastructure.
The setup can easily be extended with more web hosting nodes, and even load-balancers.

I am writing this because I want to share this solution with those of you that are interested. For a fee I will help with the installation and maintenance.

To recap, I am using four XEN virtual machines, with the following software:
* Load-balancer software: HAProxy
* Cluster filesystem: OCFS2 (Oracle Cluster Filesystem)
* Block mirroring: DRBD
* High availability: Heartbeat
* Web hosting software: cPanel, with LiteSpeed as web server.

Thanks for reading.