hadoop-2.7.4-nodemanager无法启动问题解决方案

近期新配了hadoop-274版本的集群，发现有一个小问题，DataNode无法顺利启动。
问题日志如下：

	resourcemanager_log
		2017-09-20 03:54:24,165 INFO org.apache.hadoop.yarn.server.resourcemanager.ResourceTrackerService:
		NodeManager from  ubuntu doesn't satisfy minimum allocations, 
		Sending SHUTDOWN signal to the NodeManager.
		
	nodemanager_log
		2017-09-20 03:54:24,228 ERROR org.apache.hadoop.yarn.server.nodemanager.NodeStatusUpdaterImpl: 
		Unexpected error starting NodeStatusUpdater
		Recieved SHUTDOWN signal from Resourcemanager ,Registration of NodeManager failed, 
		Message from ResourceManager: NodeManager from  ubuntu doesn't satisfy minimum allocations, 
		Sending SHUTDOWN signal to the NodeManager.

最后解决方案如下：

	在[yarn-site.xml]中添加如下属性：
		
			yarn.nodemanager.resource.cpu-vcores
			8
		
		&