I used the GUI demo to reproduce this (version=4.2.1.CR1) #1 Add <DISCARD use_gui="true"/> between UDP and PING in etc/jgroups-udp.xml #2 ./runDemo.sh for the first node #3 ./runDemo.sh for the second node #4 Start the first cache #5 In the dialog box that pops up, press "start discarding" #6 Start the second cache #7 Add data to the first and second caches (numOwners=2 by default) #8 Observe that the data is not distributed. This is correct, as we have a (simulated) network partition #9 Press "stop discarding" in the first dialog box #10 After some seconds (between 10-30 in jgroups-udp.xml), the node merge #11 However, only some of the data has been copied to the other node. With 2 nodes and numOwners=2, all the keys should be present on both nodes !