hadoop50070页面打不开以及hadoop dfsadmin -report出来的结果为

1. 50070页面打不开
   用jps命令查看发现namenode没有启动
   解决办法：删掉master和slave虚拟机的hadoop.tmp.dir，dfs.name.dir，dfs.data.dir配置的目录，重新用hadoop namenode -format 格式化，再start-all.sh
   成功

2. 在终端输入hadoop dfsadmin -report,结果如下：

[root@master hadoop]#  hdfs dfsadmin -report
Configured 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: 0
Blocks with corrupt replicas: 0
Missing blocks: 0
hadoop dfsadmin -safemode leave

方法一：关掉防火墙systemctl stop firewalld.service
失败
方法二：离开安全模式

hadoop dfsadmin -safemode leave

失败
最后按照解决50070页面打不开的方法，成功解决

[root@master hadoop_opt]# hadoop dfsadmin
-report
DEPRECATED: Use of this script to execute
hdfs command is deprecated.
Instead use the hdfs command for it.
Configured Capacity: 36477861888 (33.97 GB)
Present Capacity: 25981939712 (24.20 GB)
DFS Remaining: 25981931520 (24.20 GB)
DFS Used: 8192 (8 KB)
DFS Used%: 0.00%
Under replicated blocks: 0
Blocks with corrupt replicas: 0
Missing blocks: 0
-------------------------------------------------

看博客说，没有正确退出hadoop容易造成好多问题。
以后记住要用stop-all.sh把所有进程关掉。

防火墙命令：

1. 查看防火墙状态

firewall-cmd --state

2. 开启服务

systemctl start firewalld.service

3. 关闭服务

systemctl stop firewalld.service

4. 开机自启

systemctl enable firewalld.service

5. 关闭开机自启

systemctl disable firewalld.service