I have a 3 node flume-master setup that is backed by an external 3 node zookeeper cluster.
flume-node registers on flume-master node A. If the flume-node process is restarted/box rebooted/whatever, when it comes back up and it registers on flume-master node B, node A shows a LOST node even though the node is registered on node B.
Screenshots I'll attach:
1) beforeRestart.png shows 'cdh3collector3 registered on master (server id:1)
2) afterRestartS0.png shows 'cdh3collector3' registered on new master (server id:0)
3) deadNodeS1.png shows the old registration for 'cdh3collector3' as not seen in a long time on old master (server id:1). Eventually this changes to 'LOST'
It seems that the old registration should disappear if the node reappears on a different master node.