Jesper Söderlund not only put together a few interesting scalability patterns, he also came up with a few interesting scalability lessons: Lesson #1. Put Smarty compile and template caches on an active-active DRBD cluster with high load and your servers will DIE!Lesson #2. Don't use out-of-the-box configurations.Lesson #3. Single points of contention will eventually become a bottleneck.Lesson #4.