Time for action – formatting the NameNode

Before starting Hadoop in either pseudo-distributed or fully distributed mode for the first time, we need to format the HDFS filesystem that it will use. Type the following:

$  hadoop namenode -format

The output of this should look like the following:

$ hadoop namenode -format
12/10/26 22:45:25 INFO namenode.NameNode: STARTUP_MSG: 
/************************************************************
STARTUP_MSG: Starting NameNode
STARTUP_MSG:   host = vm193/10.0.0.193
STARTUP_MSG:   args = [-format]
…
12/10/26 22:45:25 INFO namenode.FSNamesystem: fsOwner=hadoop,hadoop
12/10/26 22:45:25 INFO namenode.FSNamesystem: supergroup=supergroup
12/10/26 22:45:25 INFO namenode.FSNamesystem: isPermissionEnabled=true
12/10/26 22:45:25 INFO common.Storage: Image file of size 96 saved in 0 seconds.
12/10/26 22:45:25 INFO common.Storage: Storage directory /var/lib/hadoop-hadoop/dfs/name has been successfully formatted.
12/10/26 22:45:26 INFO namenode.NameNode: SHUTDOWN_MSG...