NameNode，Secondary NameNode，DataNodes只是名字给机器根据他们执行的工作。在理想的分布式环境中，它们都可以并且应该驻留在单独的机器中。

NameNode, Secondary NameNode, DataNodes are just names given to "machines" based on the job they perform. In a "ideal" distributed enviornment, they all can and should reside in separate machines.

辅助NameNode在另一台机器上的唯一要求是：Secondary NameNode NamdeNode应该连接，使FSImane& EditLogs可以从NameNode复制到Secondary NameNode。

The only requirement for a secondary NameNode to be on another machine is : Secondary NameNode and NamdeNode should be connected so that The FSImane & EditLogs can be copied from NameNode to Secondary NameNode.