Minor Description
The Flume User guide says that nodes can be in one of these states: HELLO, CONFIGURING, ACTIVE, IDLE, or ERROR. There is one other state in which a node can be but which is not described: LOST. However, the documentation does mention this state in passing when describing the Flume command waitForNodesDone:
waitForNodesDone ms node1 [node2 [...]]
This command blocks for up to ms milliseconds until the specified list of nodes have entered the IDLE, ERROR, or LOST state.