Namenode loads the filesystem state from fsimage and stays in safe mode and wait for data nodes to report their blocks. Safemode is a read-only mode for HDFS cluster, so that it does not prematurely start replicating the blocks. Use following command to let the namenode leave safemode forcefully.
$ hadoop dfsadmin -safemode leave
In newer versions of hadoop command is deprecated. You can use hdfs command instead of hadoop. For example:
$ hdfs dfsadmin -safemode leave
You must run hadoop fsck so sort out any inconsistencies created in the hdfs due to above command.
thanks for posting such useful information about Hadoop namenode
Great post…! clearly explained the Hadoop namenode is in safe mode with clear explaination. Thank you..!