原创文章：http://blog.csdn.net/renfengjun/article/details/25320043
DN中日志如下：
2017-06-17 06:35:59,242 WARN org.apache.hadoop.hdfs.server.datanode.DataNode: Problem connecting to server: node1/192.168.1.128:9000
2017-06-17 06:36:05,246 INFO org.apache.hadoop.ipc.Client: Retrying connect to server: node1/192.168.1.128:9000. Already tried 0 time(s); retry policy is RetryUpToMaximumCountWithFixedSleep(maxRetries=10, sleepTime=1000 MILLISECONDS)
2017-06-17 06:36:06,250 INFO org.apache.hadoop.ipc.Client: Retrying connect to server: node1/192.168.1.128:9000. Already tried 1 time(s); retry policy is RetryUpToMaximumCountWithFixedSleep(maxRetries=10, sleepTime=1000 MILLISECONDS)
2017-06-17 06:36:07,253 INFO org.apache.hadoop.ipc.Client: Retrying connect to server: node1/192.168.1.128:9000. Already tried 2 time(s); retry policy is RetryUpToMaximumCountWithFixedSleep(maxRetries=10, sleepTime=1000 MILLISECONDS)
赖自己刚把/etc/hosts改成
127.0.0.1 localhost node1 localhost4 localhost4.localdomain4
192.168.1.128 node1
原来是
127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4
192.168.1.128 node1
hdfs启动后进入safe mode，Problem connecting to server
原文：http://www.cnblogs.com/sorco/p/7041450.html