A hard link differs from a symbolic link in that a hard link is not a pointer to another file. A hard link is two directory entries that point to the same inode number.
If the backup selection list includes hard-linked files, the data is backed up only once during a backup. NetBackup uses the first file name reference that is found in the directory structure. If a subsequent file name reference is found, it is backed up as a link to the name of the first file. Backup up only the link means that only one backup copy of the data is created, regardless of the number of hard links. Any hard link to the data works.