- 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. Plan in advance.
- Lesson #5. Offload your databases as much as possible.
- Lesson #6. File systems matter and can run out of space / inodes.
For more details and explanations see the original post.