hadoop开启集群服务时打开不了secondarynamenode

当使用命令行start-dfs.sh开启hdfs守护进程时，secondaryNamenode打开不了，卡顿在
Starting namenodes on [sam01]
sam01: starting namenode, logging to /usr/local/hadoop/logs/hadoop-root-namenode-sam01.out
sam02: starting datanode, logging to /usr/local/hadoop/logs/hadoop-root-datanode-sam02.out
sam01: starting datanode, logging to /usr/local/hadoop/logs/hadoop-root-datanode-sam01.out
sam03: starting datanode, logging to /usr/local/hadoop/logs/hadoop-root-datanode-sam03.out

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此时是因为免密登录没有设置好，只需把每台机器各自的公私钥发给其余机器，并且也发给自己一份

[root@sam01 ~]# ssh-copy-id sam01