[ http://jira.jboss.com/jira/browse/JBAS-4229?page=all ] Brian Stansberry updated JBAS-4229: ----------------------------------- Fix Version/s: JBossAS-4.2.0.GA Affects Version/s: JBossAS-4.2.0.CR1 JBossAS-4.0.5.GA JBossAS-4.0.4.GA -- This message is automatically generated by JIRA. - If you think it was sent incorrectly contact one of the administrators: http://jira.jboss.com/jira/secure/Administrators.jspa - For more information on JIRA, see: http://www.atlassian.com/software/jira

[ http://jira.jboss.com/jira/browse/JBAS-4229?page=all ] Brian Stansberry updated JBAS-4229: ----------------------------------- Description: The HASingletonController doesn't understand the "split brain" problem. Take for example a JBossMQ destination (queue) which needs to be "restored" from the database when a new singleton is elected. The scenario goes as follows: STEP1 (original state): cluster=server1, server2 master=server1 STEP2 (unplug server1 from the network): cluster=server2 master=server2 server2 will now restore the queue from the database BUT! server1 has the view cluster=server1 master=server1 STEP3 (plug server1 back into the network) cluster=server1, server2 master=server1 We are back to the original state, but since server1 thinks it never left the cluster, it doesn't restore the changes (from the database) that server2 made to the queue between STEP2 and STEP3. This is because it doesn't restart the HASingleton on server1. There needs to be some extra processing in the "merge" when two masters agree to form a cluster that ensures that whoever they elect as the new master gets its HASingleton(s) restarted. Otherwise, it won't have the up-to-date state from the other master. was: The HASingletonController doesn't understand the "split brain" problem. Take for example a JBossMQ destination (queue) which needs to be "restored" from the database when a new singleton is elected. The scenario goes as follows: STEP1 (original state): cluster=server1, server2 master=server1 STEP2 (unplug server1 from the network): cluster=server2 master=server2 server2 will now restore the queue from the database BUT! server1 has the view cluster=server1 master=server1 STEP3 (plug server1 back into the network) cluster=server1, server2 master=server1 We are back to the original state, but since server1 thinks it never left the cluster, it doesn't restore the changes (from the database) that server2 made to the queue between STEP2 and STEP3. This is because it doesn't restart the HASingleton on server1. If there was a third server (server3) to abitrate this wouldn't be a problem. Both server2 and server3 would agree that server2 is the master and that server1 has left and must rejoin. There needs to be some extra processing in the "merge" when two masters agree to form a cluster that ensures that whoever they elect as the new master gets its HASingleton(s) restarted. Otherwise, it won't have the up-to-date state from the other master. Edited description to remove discussion of how presence of a 3rd server would avoid the problem. In the case of a merge, it wouldn't. -- This message is automatically generated by JIRA. - If you think it was sent incorrectly contact one of the administrators: http://jira.jboss.com/jira/secure/Administrators.jspa - For more information on JIRA, see: http://www.atlassian.com/software/jira