For copying between two different versions of Hadoop, you will usually use
HftpFileSystem. This is a read-only FileSystem, so DistCp must be run on the
destination cluster (more specifically, on NodeManagers that can write to the
destination cluster). Each source is specified as
hftp://<dfs.http.address>/<path> (the default
dfs.http.address is <namenode>:50070 ).
