From the SAN File System client perspective (and therefore from the backup application perspective), a fileset looks exactly like a regular subdirectory. From the metadata server and administrative server perspective, however, this is a fileset that is attached to an arbitrary subdirectory in the global namespace.
When a fileset resides within a directory, backup applications automatically create subdirectories when attempting to restore files to a directory that does not exist. In SAN File System, the subdirectory being created might have originally been part of another directory.
The mkdrfile command saves state information that you can use later to recreate this portion of the SAN File System if there is a disastrous loss of data. Because you can create regular subdirectories only from a client machine, the metadata server cannot recreate directory trees that contain a mix of filesets within subdirectories, and regular subdirectories. To simplify disaster recovery, attach filesets only to the global fileset (root directory) or to each other, but not to regular subdirectories. You can then use the disaster-recovery file created by the mkdrfile command to completely restore the top of the global namespace tree before using the client-based backup application to restore the rest of the global namespace.
Parent topic: Backup and restore
Parent topic: Planning the backup and restore strategy
Related reference
mkdrfile