1.搭建完hadoop后，出现“Unhealthy Nodes”不安全的节点
解决方法：在/opt/modules/hadoop-2.5.0/logs路径下查看resourcemanager用户日志，找到对应原因
NodeManager from node bigdata-01(cmPort: 38395 httpPort: 8042) registered with capability: <memory:8192, vCores:8>, assigned nodeId bigdata-01:38395
This happens when you don't have write access to the folder listed (in this case,/tmp/nodemanagerLog). To fix the problem, change this directory in your -site.xml file.
看来是因为我是以root用户在R上运行mapreduce，对log路径没有写权限，所以才会导致这个错误。。。
修改权限为777后重启hadoop，问题解决！
chmod 777 logs
sbin/yarn-daemon.sh start resourcemanager
sbin/yarn-daemon.sh start nodemanager