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搭建HA集群，格式化namenode，一直出现这种现象，说我的集群6连接不上
百度，试了很多种方法，还是不行，
最后进入cluster-6查看防火墙是否开着，
利用命令
systemctl status firewalld结果防火墙正在运行，如下所示：
[root@cluster-6 logs]# systemctl status firewalld
● firewalld.service - firewalld - dynamic firewall daemon
Loaded: loaded (/usr/lib/systemd/system/firewalld.service; enabled; vendor preset: enabled)
Active: active (running) since 四 2019-01-24 16:51:12 CST; 5h 48min ago
Docs: man:firewalld(1)
Main PID: 6562 (firewalld)
CGroup: /system.slice/firewalld.service
└─6562 /usr/bin/python -Es /usr/sbin/firewalld --nofork --nopid
1月 24 16:50:56 cluster-6 systemd[1]: Starting firewalld - dynamic firewall daemon...
1月 24 16:51:12 cluster-6 systemd[1]: Started firewalld - dynamic firewall daemon.
马上利用命令将防火墙关闭：
systemctl stop firewalld再进行格式化，./hdfs namenode -format
就成功了，如下所示：
19/01/24 22:45:24 INFO common.Storage: Storage directory /usr/local/hadoop-2.8.5/tmp/dfs/name has been successfully formatted.
19/01/24 22:45:25 INFO namenode.FSImageFormatProtobuf: Saving image file /usr/local/hadoop-2.8.5/tmp/dfs/name/current/fsimage.ckpt_0000000000000000000 using no compression
19/01/24 22:45:25 INFO namenode.FSImageFormatProtobuf: Image file /usr/local/hadoop-2.8.5/tmp/dfs/name/current/fsimage.ckpt_0000000000000000000 of size 321 bytes saved in 0 seconds.
19/01/24 22:45:25 INFO namenode.NNStorageRetentionManager: Going to retain 1 images with txid >= 0
19/01/24 22:45:25 INFO util.ExitUtil: Exiting with status 0
19/01/24 22:45:25 INFO namenode.NameNode: SHUTDOWN_MSG:
/************************************************************
SHUTDOWN_MSG: Shutting down NameNode at cluster-1/192.168.79.131
************************************************************/