18/01/07 02:05:32 INFO ipc.Client: Retrying connect to server: master/192.168.157.10:9000. Already tried 0 time(s); retry policy is RetryUpToMaximumCountWithFixedSleep(maxRetries=10, sleepTime=1 SECONDS)
18/01/07 02:05:33 INFO ipc.Client: Retrying connect to server: master/192.168.157.10:9000. Already tried 1 time(s); retry policy is RetryUpToMaximumCountWithFixedSleep(maxRetries=10, sleepTime=1 SECONDS)
18/01/07 02:05:34 INFO ipc.Client: Retrying connect to server: master/192.168.157.10:9000. Already tried 2 time(s); retry policy is RetryUpToMaximumCountWithFixedSleep(maxRetries=10, sleepTime=1 SECONDS)
18/01/07 02:05:35 INFO ipc.Client: Retrying connect to server: master/192.168.157.10:9000. Already tried 3 time(s); retry policy is RetryUpToMaximumCountWithFixedSleep(maxRetries=10, sleepTime=1 SECONDS)
18/01/07 02:05:36 INFO ipc.Client: Retrying connect to server: master/192.168.157.10:9000. Already tried 4 time(s); retry policy is RetryUpToMaximumCountWithFixedSleep(maxRetries=10, sleepTime=1 SECONDS)

解决方法：

1、重启hadoop集群
* 进入hadoop的安装目录：cd /usr/local/src/bin
* 关闭所有节点： ./stop-all.sh
* namenode格式化：hadoop namenode-format (注意：选择Y)
* 开启所有的节点：./start-all.sh
2、防火墙没有关闭
* chkconfig iptables off：防火墙开机不自启动，并不是关闭防火墙
* 清空系统防火墙
iptables -F
* 保存防火墙配置
service iptables save
* 临时关闭内核防火墙
setenforce 0
* 永久关闭内核防火墙
vim /etc/selinux/config
SELINUX=disabled