I agree that a solution needs to exist for O/L and P/L as well as MVCC - not only because we don't have MVCC right now, but also because even after we do, people will still have the choice to use the more tried-and-tested O/L and P/L. Regarding responding positively to a prepare, perhaps I'm missing something here - why would it be wrong for new joiner - D - to respond positively? Let's look at it the other way around. Why would an existing node, say, C, respond negatively? IMO there are only 2 scenarios where C would respond negatively to a prepare from A: 1. There is another local transaction on C that holds locks on the same data. 2. There is another concurrent prepare, say from B, on the same data. (Have I missed anything?) Now neither of these reasons for a negative response to a prepare should apply to the new joiner, D: 1. would never happen since the new joiner hasn't reached the STARTED state and isn't accepting any local transactions. 2. D doesn't care about conflicting remote prepares since at least someone else in the cluster would have detected this and the prepare would roll back anyway. E.g., if A and B broadcast prepares on the same data and D responds positively to both, either A or B will fail on each other's prepares and broadcast a rollback anyway. Thoughts? View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4113205#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...