I think the largest clusters I've seen (with 1.4.x) has been with close to 50 instances, but that''s using async replication. If you want sync replication, and you can guarantee session affinity, I'd recommend buddy replication since this scales very well compared to total replication. Hopefully in the near future we'll have a much more scalable replication mechanism http://wiki.jboss.org/wiki/Wiki.jsp?page=JBossCachePartitioning View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4098809#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...