出现的错误如下：
hadoop@mike-VirtualBox:/usr/local/hadoop/hadoop$ ./sbin/start-dfs.sh 20/12/14 20:15:06 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable Starting namenodes on [localhost] localhost: namenode running as process 8844. Stop it first. localhost: datanode running as process 9057. Stop it first. Starting secondary namenodes [0.0.0.0] 0.0.0.0: secondarynamenode running as process 9312. Stop it first. 20/12/14 20:15:19 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
解决方法是首先停止启动所有的节点，使用命令行启动stop-all.sh脚本：
./sbin/stop-all.sh
然后再次重新启动start-dfs.sh脚本，如下所示：
hadoop@mike-VirtualBox:/usr/local/hadoop/hadoop$ ./sbin/start-dfs.sh Starting namenodes on [localhost] localhost: starting namenode, logging to /usr/local/hadoop/hadoop/logs/hadoop-hadoop-namenode-mike-VirtualBox.out localhost: starting datanode, logging to /usr/local/hadoop/hadoop/logs/hadoop-hadoop-datanode-mike-VirtualBox.out Starting secondary namenodes [0.0.0.0] 0.0.0.0: starting secondarynamenode, logging to /usr/local/hadoop/hadoop/logs/hadoop-hadoop-secondarynamenode-mike-VirtualBox.out
这样就成功启动了！
觉得有用的哥们儿麻烦在下面点赞，关注一下呗！
【Hadoop】：配置出错error出现：Stop it first
原文：https://www.cnblogs.com/geeksongs/p/14135079.html