在搭建好Hadoop集群之后，所有服务均可正常启动，但是在运行MapReduce程序的时候，发现任务卡在7/09/07 22:28:14 INFO mapreduce.Job: Running job: job_1504781778966_0003，不再往下执行了，经过检查，发现所有的nodes节点都处于unhealthy的状态，使用命令查看node 的状态
bin/yarn node -list -all
查看日志发现
2015-07-16 15:28:58,643 WARN org.apache.hadoop.yarn.server.nodemanager.DirectoryCollection: Directory /opt/beh/data/yarn/nmlocal error, used space above threshold of 90.0%, removing from list of valid directories
2015-07-16 15:28:58,645 WARN org.apache.hadoop.yarn.server.nodemanager.DirectoryCollection: Directory /opt/beh/logs/yarn/nmlogs error, used space above threshold of 90.0%, removing from list of valid directories
2015-07-16 15:28:58,645 INFO org.apache.hadoop.yarn.server.nodemanager.LocalDirsHandlerService: Disk(s) failed: 1/1 local-dirs are bad: /opt/beh/data/yarn/nmlocal; 1/1 log-dirs are bad: /opt/beh/logs/yarn/nmlogs
2015-07-16 15:28:58,645 ERROR org.apache.hadoop.yarn.server.nodemanager.LocalDirsHandlerService: Most of the disks failed. 1/1 local-dirs are bad: /opt/beh/data/yarn/nmlocal; 1/1 log-dirs are bad: /opt/beh/logs/yarn/nmlogs
是node的内存不足导致的！
解决方法
* 1 把节点上的不用的东西删完，删到90%以下即可
* 2 在yarn-site.xml中添加以下配置信息，修改上限和下限
<property>
<name>yarn.nodemanager.disk-health-checker.min-healthy-disks</name>
<value>0.0</value>
</property>
<property>
<name>yarn.nodemanager.disk-health-checker.max-disk-utilization-per-disk-percentage</name>
<value>100.0</value>
</property>
再重启服务 问题解决