When sending LargeMessages (server2client), I need to have the masterNode inform the backupNode what's happening on the sending. The process of sending small messages on clustering seems simple to me, as you can do it atomically. You inform the backup about sending the message, and the backup will place it on the buffer. And receiving the confirmation on flow-control is also simple. However on largeMessages this is a little bit different: I - I inform the backup node that I'm starting a MessageSend, so the backup-node will take out the delivery from the queue, and create the LargeMessages. II - I can't just let the backup-node call largeMessageSender.send, or the backup could be running faster than the server. (Running out of Credits first for instance). So I'm currently implementing it in a way the live-node is aways informing the backup-node what position of the LargeMessage is being sent to the client. In case of failure the backup-node will resume from that chunk forward. (of course using the logic that is already in place for packet confirmation). Another option I have is reset everything and start sending large message again from its beginning in case of failure. I will check that option tomorrow. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4197484#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...