标签：hadoop 安全设置。reported system turned
hadoop启动时报如下错误：错误分别在namenode和jobTracker日志文件都有
org.apache.hadoop.hdfs.server.namenode.SafeModeException: Cannot delete /usr/hadoop/tmp/mapred/system. Name node is in safe mode.
The ratio of reported blocks 1.0000 has reached the threshold 0.9990. Safe mode will be turned off automatically in 27 seconds.
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.run(Server.java:1382)
原因：
hadoop默认情况下在安全模式运行。可以通过下面hadoop dfsadmin -safemode 参数,查看相关的状态和设置安全模块是否启用。
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，一直到安全模式结束。
解决办法有二种：
《1》可能运行命令hadoop dfsadmin -safemode leave 离开安全模式，但是每次都需要手动去设置。
《2》通过配置dfs.safemode.threshold.pct的参数。默认情况下是0.9990f。这个配置可以在hdfs-defalut.xml中找到。我们可以把这个参数配置为0，永久关闭安全模式。
在hadoop中的hdfs-site.xml添加如下配置：
<property>
<name>dfs.safemode.threshold.pct</name>
<value>0f</value>
<description>
Specifies the percentage of blocks that should satisfy
the minimal replication requirement defined by dfs.replication.min.
Values less than or equal to 0 mean not to wait for any particular
percentage of blocks before exiting safemode.
Values greater than 1 will make safe mode permanent.
</description>
</property>
重启NameNode就可以了。
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hadoop1安全异常：The ratio of reported blocks 1.0000 has reached the threshold 0.9990.
标签：hadoop 安全设置。reported system turned
原文地址：http://472053211.blog.51cto.com/3692116/1577108
