Solutions like Linux Heartbeat can do the job, too.

Our setup involves 150+ RH boxes. This is not just LAMP webservers but all of the MySQL apps servers - we are on a SAN so failing over for several unrelated apps can be relegated to one server, since if all the servers servers failed at once we would be in disaster mode, failing to a remote site.

You must have an I/O problem with your setup - relegating reads ands writes to separate boxes.