Direct access is convenient but not terribly efficient because NFS is limited in the bandwidth it can supply.
Indirect access is less convenient but offers much higher performance.
Login access is restricted to non-compute intensive commands and can be used for monitoring and managing migrated files through the dmls, dmfind and dmget commands. The operation and policies of DMF are described below. The files are removed from the disk, but their inodes remain in tact, and marked with a migration flag. Any attempt to access a migrated file signals DMF to automatically retrieve the file from the archive. Any command accessing a migrated file simply waits for the retrieval.