>> Which package in the >> source code could I look at to glean this information ?
>This is in dfs/FSNameSystem.java. FSNameSystem.java is a huge chunk of source code. To be more specific, datanode failure detection is done by HeartbeatMonitor. Once a data node is detected as dead, all blocks belonged to this data node will be put in neededReplications queue. Then the ReplicationMonitor will start to replicate those under-replicated blocks. All the replication target chosen logic is in dfs/ReplicationTargetChooser.java. Hairong
