Hadoop SecondNamenode详解
SecondNamenode名字看起来很象是第二个NameNode,要么与NameNode一样同时对外提供服务,要么相当于NameNode的HA。真正的了解了SecondNameNode以后,才发现事实并不是这样的。 下面这段是Hadoop对SecondNameNode的准确定义: *The Secondary NameNode is a helper to the primary NameNode. *The Secondary is responsible for supporting periodic checkopoints