Hadoop exception record cannot delete/tmp/hadoop/mapred/system. Name node is in safe mode.

Source: Internet
Author: User
Org. apache. hadoop. IPC. remoteException: Org. apache. hadoop. HDFS. server. namenode. safemodeexception: cannot delete/tmp/hadoop/mapred/system. name node is in safe mode.
The ratio of reported blocks 0.7857 has not reached the threshold 0.9990. Safe mode will be turned off automatically.
At org. Apache. hadoop. HDFS. server. namenode. fsnamesystem. deleteinternal (fsnamesystem. Java: 1992)
At org. Apache. hadoop. HDFS. server. namenode. fsnamesystem. Delete (fsnamesystem. Java: 1972)
At org. Apache. hadoop. HDFS. server. namenode. namenode. Delete (namenode. Java: 792)
At sun. Reflect. nativemethodaccessorimpl. invoke0 (native method)
At sun. Reflect. nativemethodaccessorimpl. Invoke (nativemethodaccessorimpl. Java: 39)
At sun. Reflect. delegatingmethodaccessorimpl. Invoke (delegatingmethodaccessorimpl. Java: 25)
At java. Lang. Reflect. method. Invoke (method. Java: 597)
At org. Apache. hadoop. IPC. RPC $ server. Call (RPC. Java: 563)
At org. Apache. hadoop. IPC. Server $ handler $ 1.run( server. Java: 1388)
At org. Apache. hadoop. IPC. Server $ handler $ 1.run( server. Java: 1384)
At java. Security. accesscontroller. doprivileged (native method)
At javax. Security. Auth. Subject. DOAs (subject. Java: 396)
At org. Apache. hadoop. Security. usergroupinformation. DOAs (usergroupinformation. Java: 1083)
At org. Apache. hadoop. IPC. Server $ handler. Execute (server. Java: 1382)

Do not worry. namenode will automatically disable the security mode at the start stage, and then start successfully. If you do not want to wait, run:

Bin/hadoop dfsadmin-safemode leave force termination.

Explanation: Security Mode

When namenode is started, it will load the status information of the file system from the fsimage and edits log files, and then it waits for each datanode to report the status of their respective data blocks to it. In this way, namenode does not start copying data blocks too early, even if there are sufficient copies. At this stage, namenode is in safe mode. The security mode of namenode is essentially a read-only mode for HDFS clusters. At this time, the cluster does not allow any modifications to the file system or data block. Generally, namenode automatically exits the security mode at the beginning. If necessary, you can use the 'bin/hadoop dfsadmin-safemode' command to explicitly place HDFS in safe mode. The namenode homepage displays whether the current security mode is enabled. For more information about security mode and configuration, see javadoc: setsafemode ().

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