1）防火墙没关闭、或者没有启动yarnx
INFO client.RMProxy: Connecting to ResourceManager at hadoop108/192.168.10.108:8032
2）主机名称配置错误
3）ip地址配置错误
4）ssh没有配置好
5）root用户和atguigu两个用户启动集群不统一
6）配置文件修改不细心
7）未编译源码
Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
17/05/22 15:38:58 INFO client.RMProxy: Connecting to ResourceManager at hadoop108/192.168.10.108:8032
8）datanode不被namenode识别问题
Namenode在format初始化的时候会形成两个标识，blockPoolId和clusterId。新的datanode加入时，会获取这两