[zhangbin@hadoop102 hadoop-3.3.0]$ sbin/start-dfs.sh
异常信息：
hadoop102: ERROR: Cannot set priority of namenode process 35346
解决方法：
切换到hadoop日志目录：
[zhangbin@hadoop102 hadoop-3.3.0]$ cd logs/
查看日志信息：
[zhangbin@hadoop102 logs]$ cat hadoop-zhangbin-namenode-hadoop102.log
异常信息大体为这样：
2021-04-05 10:21:36,656 INFO org.apache.hadoop.http.HttpServer2: HttpServer.start() threw a non Bind IOException
java.net.BindException: Port in use: hadoop102:9870
at org.apache.hadoop.http.HttpServer2.constructBindException(HttpServer2.java:1292)
at org.apache.hadoop.http.HttpServer2.bindForSinglePort(HttpServer2.java:1314)
at org.apache.hadoop.http.HttpServer2.openListeners(HttpServer2.java:1373)
at org.apache.hadoop.http.HttpServer2.start(HttpServer2.java:1223)
at org.apache.hadoop.hdfs.server.namenode.NameNodeHttpServer.start(NameNodeHttpServer.java:170)
at org.apache.hadoop.hdfs.server.namenode.NameNode.startHttpServer(NameNode.java:946)
at org.apache.hadoop.hdfs.server.namenode.NameNode.initialize(NameNode.java:757)
at org.apache.hadoop.hdfs.server.namenode.NameNode.<init>(NameNode.java:1014)
at org.apache.hadoop.hdfs.server.namenode.NameNode.<init>(NameNode.java:987)
at org.apache.hadoop.hdfs.server.namenode.NameNode.createNameNode(NameNode.java:1756)
at org.apache.hadoop.hdfs.server.namenode.NameNode.main(NameNode.java:1821)
Caused by: java.io.IOException: Failed to bind to hadoop102/192.168.10.102:9870
at org.eclipse.jetty.server.ServerConnector.openAcceptChannel(ServerConnector.java:346)
at org.eclipse.jetty.server.ServerConnector.open(ServerConnector.java:307)
at org.apache.hadoop.http.HttpServer2.bindListener(HttpServer2.java:1279)
at org.apache.hadoop.http.HttpServer2.bindForSinglePort(HttpServer2.java:1310)
... 9 more
Caused by: java.net.BindException: 地址已在使用
at sun.nio.ch.Net.bind0(Native Method)
at sun.nio.ch.Net.bind(Net.java:433)
at sun.nio.ch.Net.bind(Net.java:425)
at sun.nio.ch.ServerSocketChannelImpl.bind(ServerSocketChannelImpl.java:223)
at sun.nio.ch.ServerSocketAdaptor.bind(ServerSocketAdaptor.java:74)
at org.eclipse.jetty.server.ServerConnector.openAcceptChannel(ServerConnector.java:342)
... 12 more
解决方法：找到到占用端口，并杀死
[zhangbin@hadoop102 logs]$ lsof -i:9870 -P
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
java 22003 zhangbin 289u IPv4 89125 0t0 TCP hadoop102:9870 (LISTEN)
[zhangbin@hadoop102 logs]$ kill -9 22003
重新启动即可
解决办法：
停止所有hadoop节点的所有服务
删除每个服务节点（服务器）中的DataNode里面的信息（默认在/tmp，我的在DataNode信息配置在了hadoop项目根目录的data中， 并且删除hadoop下的logs目录，删除这两个目录里的所有文件）
重新格式化hadoop：指令：
hdfs namenode -format
启动hadoop服务即可