啟動的時候，一直要求輸入namenode密碼：
查看namenode的日志如下：
2019-03-28 18:38:08,961 INFO org.apache.hadoop.ipc.Client: Retrying connect to server: datanode1/192.168.197.136:8485. Already tried 47 time(s); retry policy is RetryUpToMaximumCountWithFixedSleep(maxRetries=100, sleepTime=10000 MILLISECONDS)
2019-03-28 18:38:09,208 INFO org.apache.hadoop.ipc.Client: Retrying connect to server: namenode2/192.168.197.135:8030. Already tried 29 time(s); retry policy is RetryUpToMaximumCountWithFixedSleep(maxRetries=100, sleepTime=10000 MILLISECONDS)
2019-03-28 18:38:18,958 INFO org.apache.hadoop.ipc.Client: Retrying connect to server: datanode2/192.168.197.137:8485. Already tried 48 time(s); retry policy is RetryUpToMaximumCountWithFixedSleep(maxRetries=100, sleepTime=10000 MILLISECONDS)
2019-03-28 18:38:18,961 INFO org.apache.hadoop.ipc.Client: Retrying connect to server: datanode3/192.168.197.138:8485. Already tried 48 time(s); retry policy is RetryUpToMaximumCountWithFixedSleep(maxRetries=100, sleepTime=10000 MILLISECONDS)
懷疑是其他服務器，namenode2/192.168.197.135，datanode1/192.168.197.136，datanode2/192.168.197.137，datanode3/192.168.197.138
上面沒有authorized_keys文件中namenode1/192.1682.197.134的公鑰不對。
在namenode1/192.1682.197.134中重新執行ssh-keygen -t rsa，生成公鑰和私鑰，發現私鑰真的和其他服務器上存儲的namenode1/192.1682.197.134的公鑰不匹配。
更改其他服務器上authorized_keys中namenode1/192.1682.197.134的公鑰后，重啟hdfs正常啟動。
