Description of the illustration bigug_vm_004.eps

This diagram of automatic failover shows the following relationships:

Two failover controllers have lines pointing to the ZooKeeper. Each failover controller has lines pointing to a NameNode on the same server (1 or 2). The NameNode on server 1 is in active mode, and the NameNode on server 2 is in hot standby mode.

The NameNodes have lines pointing to the three JournalNodes. The active NameNode has lines pointing to the three DataNodes, and they have lines pointing to both NameNodes.

The standby NameNode has a checkpoint line to the active NameNode.