I have 1 dedicated mysql server, 1 haproxy balancer server, and 2 identical (in terms of os (ubuntu 12.04.1 server) and lamp version) web servers, running load balanced with haproxy, to handle high user activities of users on moodle. Both interact with separate mysql server in similar way, but the "moodledata" (on first server) folder is shared by nfs file sharing with 2nd server. Every thing seem to work pretty fine in testing but now a days when there is some quiz activities going on at moodle, my first server (which was there initially) works ok, but the other server (newly added) goes very high on load and haproxy stops sending request on it, and mark it as "down". The "w" command on first server gives load average less than one, but it gives load average >100 sometimes on 2nd server. From than no load balancing is happening, the system only runs on 1 server.
