Hadoop错误9_解决Hadoop的Safe mode is ON问题

好久没启动Hadoop集群，今天启动后发现出了一些问题：

启动后，输入jps命令，发现Namenode节点没有启动，问题描述如下：

<p><span style="font-family: Arial, Helvetica, sans-serif; font-size: 12px;">[hadoop@Master hadoop]$ jps</span></p><p>33100 ResourceManager33358 Jps32957 SecondaryNameNode</p>

同样，输入bin/hdfs dfsadmin -report查看各个节点的状态，也显示失败：

[hadoop@Master hadoop]$ bin/hdfs dfsadmin -report15/09/23 19:30:05 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicableSafe mode is ONConfigured Capacity: 0 (0 B)Present Capacity: 0 (0 B)DFS Remaining: 0 (0 B)DFS Used: 0 (0 B)DFS Used%: NaN%Under replicated blocks: 0Blocks with corrupt replicas: 0Missing blocks: 0-------------------------------------------------report: Access denied for user hadoop. Superuser privilege is required[hadoop@Master hadoop]$ 

查找解决方法，按一下方法解决：

[hadoop@Master hadoop]$  hadoop dfsadmin -safemode leaveDEPRECATED: Use of this script to execute hdfs command is deprecated.Instead use the hdfs command for it.15/09/23 19:37:11 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicablesafemode: Access denied for user hadoop. Superuser privilege is required[hadoop@Master hadoop]$ suPassword: [root@Master hadoop]#  hadoop dfsadmin -safemode leaveDEPRECATED: Use of this script to execute hdfs command is deprecated.Instead use the hdfs command for it.15/09/23 19:37:33 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicableSafe mode is OFF[root@Master hadoop]# 

需要在root用户下，输入hadoop dfsadmin -safemode leave

再次启动，发现成功：

[hadoop@Master hadoop]$ bin/hdfs dfsadmin -report15/09/23 19:42:26 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicableSafe mode is ONConfigured Capacity: 37558796288 (34.98 GB)Present Capacity: 22514479104 (20.97 GB)DFS Remaining: 22513803264 (20.97 GB)DFS Used: 675840 (660 KB)DFS Used%: 0.00%Under replicated blocks: 0Blocks with corrupt replicas: 0Missing blocks: 0-------------------------------------------------Live datanodes (2):Name: 192.168.154.159:50010 (Slave2)Hostname: Slave2Decommission Status : NormalConfigured Capacity: 18779398144 (17.49 GB)DFS Used: 28672 (28 KB)Non DFS Used: 6979022848 (6.50 GB)DFS Remaining: 11800346624 (10.99 GB)DFS Used%: 0.00%DFS Remaining%: 62.84%Configured Cache Capacity: 0 (0 B)Cache Used: 0 (0 B)Cache Remaining: 0 (0 B)Cache Used%: 100.00%Cache Remaining%: 0.00%Xceivers: 1Last contact: Wed Sep 23 19:42:25 PDT 2015Name: 192.168.154.158:50010 (Slave1)Hostname: Slave1Decommission Status : NormalConfigured Capacity: 18779398144 (17.49 GB)DFS Used: 647168 (632 KB)Non DFS Used: 8065294336 (7.51 GB)DFS Remaining: 10713456640 (9.98 GB)DFS Used%: 0.00%DFS Remaining%: 57.05%Configured Cache Capacity: 0 (0 B)Cache Used: 0 (0 B)Cache Remaining: 0 (0 B)Cache Used%: 100.00%Cache Remaining%: 0.00%Xceivers: 1Last contact: Wed Sep 23 19:42:25 PDT 2015[hadoop@Master hadoop]$ 

附录：

dfsadmin -safemode value 参数value的说明如下：
enter - 进入安全模式
leave - 强制NameNode离开安全模式
get -  返回安全模式是否开启的信息
wait - 等待安全模式结束。

查找解决方法，按一下方法解决：