Ambari安装后NameNode无法启动

[Jasonty]

这个问题我折腾一天半了，实在无解，所以来求助论坛的高手。
首先我保证我的cluster中的机器防火墙都关闭了，Selinux也都关闭了，NameNode无法启动报的错误如下

stderr: 

 stdout:
safemode: Call From master/9.119.131.105 to master:8020 failed on connection exception: java.net.ConnectException: Connection refused; For more details see:  http://wiki.apache.org/hadoop/ConnectionRefused
2016-04-13 14:36:09,293 - Retrying after 10 seconds. Reason: Execution of '/usr/hdp/current/hadoop-hdfs-namenode/bin/hdfs dfsadmin -fs hdfs://master:8020 -safemode get | grep 'Safe mode is OFF'' returned 1. safemode: Call From master/9.119.131.105 to master:8020 failed on connection exception: java.net.ConnectException: Connection refused; For more details see:  http://wiki.apache.org/hadoop/ConnectionRefused
safemode: Call From master/9.119.131.105 to master:8020 failed on connection exception: java.net.ConnectException: Connection refused; For more details see:  http://wiki.apache.org/hadoop/ConnectionRefused
2016-04-13 14:36:22,404 - Retrying after 10 seconds. Reason: Execution of '/usr/hdp/current/hadoop-hdfs-namenode/bin/hdfs dfsadmin -fs hdfs://master:8020 -safemode get | grep 'Safe mode is OFF'' returned 1. safemode: Call From master/9.119.131.105 to master:8020 failed on connection exception: java.net.ConnectException: Connection refused; For more details see:  http://wiki.apache.org/hadoop/ConnectionRefused
safemode: Call From master/9.119.131.105 to master:8020 failed on connection exception: java.net.ConnectException: Connection refused; For more details see:  http://wiki.apache.org/hadoop/ConnectionRefused
2016-04-13 14:36:35,339 - Retrying after 10 seconds. Reason: Execution of '/usr/hdp/current/hadoop-hdfs-namenode/bin/hdfs dfsadmin -fs hdfs://master:8020 -safemode get | grep 'Safe mode is OFF'' returned 1. safemode: Call From master/9.119.131.105 to master:8020 failed on connection exception: java.net.ConnectException: Connection refused; For more details see:  http://wiki.apache.org/hadoop/ConnectionRefused
safemode: Call From master/9.119.131.105 to master:8020 failed on connection exception: java.net.ConnectException: Connection refused; For more details see:  http://wiki.apache.org/hadoop/ConnectionRefused
2016-04-13 14:36:48,643 - Retrying after 10 seconds. Reason: Execution of '/usr/hdp/current/hadoop-hdfs-namenode/bin/hdfs dfsadmin -fs hdfs://master:8020 -safemode get | grep 'Safe mode is OFF'' returned 1. safemode: Call From master/9.119.131.105 to master:8020 failed on connection exception: java.net.ConnectException: Connection refused; For more details see:  http://wiki.apache.org/hadoop/ConnectionRefused
safemode: Call From master/9.119.131.105 to master:8020 failed on connection exception: java.net.ConnectException: Connection refused; For more details see:  http://wiki.apache.org/hadoop/ConnectionRefused
2016-04-13 14:37:01,748 - Retrying after 10 seconds. Reason: Execution of '/usr/hdp/current/hadoop-hdfs-namenode/bin/hdfs dfsadmin -fs hdfs://master:8020 -safemode get | grep 'Safe mode is OFF'' returned 1. safemode: Call From master/9.119.131.105 to master:8020 failed on connection exception: java.net.ConnectException: Connection refused; For more details see:  http://wiki.apache.org/hadoop/ConnectionRefused

目测是safemode无法退出
我尝试了网上的两种方法，其一是更改dfs.namenode.threshold-pct的默认值0.999改为0.8，依然不行
第二种用命令hdfs dfsadmin -safemode forceExit，但是仍然出现这个错误：

safemode: Call From master/9.119.131.105 to master:8020 failed on connection exception: java.net.ConnectException: Connection refused; For more details see:  http://wiki.apache.org/hadoop/ConnectionRefused

看起来是8020端口没有打开
于是我又

root@master:~# nmap master -p 8020

发现8020的state 是closed

然后就是各种尝试都打不开，实在无解了，特来求助，谢谢各位。

[lida_java]

哥们，这个问题解决了吗？我也遇到同样的问题了，求解！

[Tina_1024]

是你的namenode没有起来所以无法连接。通过命令去启动namenode： /usr/hdp/current/hadoop-client/sbin/hadoop-daemon.sh --config /usr/hdp/current/hadoop-client/conf start namenode

[qq_37741356]

# su hdfs //切换到hdfs用户，若关闭了hdfs的权限则可略过这一步 # hadoop dfsadmin -safemode leave //让namenode离开安全模式 这样就可以解决问题。