I have some doubts on the performance of clustering and session management in load balanced environment. Here are my questions:

* What are the drawbacks of sticky-sessions and session replication. The cluster will contain 4 nodes, but many concurrent user sessions may be expected.
* What is the heavy load performance of both solutions?
* Have anyone used any of them in a production environment?
* How about scalability?
* If using persistent shared sessions - where to store the state to achieve a possibly fast and stable solution?
* Have you got any experience with session sharing (in external memcache, database etc.) in a big scale?

Thanks for any advice