hadoop如何添加节点
???<property> <name>dfs.balance.bandwidthPerSec</name> <value>1048576</value> <description> Specifies the maximum amount of bandwidth that each datanode can utilize for the balancing purpose in term of the number of bytes per second. </description></property>

注意：
1. 必须确保slave的firewall已关闭;
2. 确保新的slave的ip已经添加到master及其他slaves的/etc/hosts中，反之也要将master及其他slave的ip添加到新的slave的/etc/hosts中