Cluster
From MoodleDocs
When I have more time I will update this page with more information (most likely the real-world experience that we had here in San Francisco State University) - Wen
To begin with, here are some interesting discussion about running moodle in a cluster configuration:
TCP Load Balancing Discussion http://moodle.org/mod/forum/discuss.php?d=49986
Moodle Clustering http://moodle.org/mod/forum/discuss.php?d=57202
Installation for 3000 simultaneous users http://moodle.org/mod/forum/discuss.php?d=88214