1. A method for performing a backup of a stub object located on a file system managed by a hierarchical storage manager configured to migrate data objects from the file system to a migration storage pool, the stub object including information for recalling a migrated data object, the method comprising: determining whether a backup copy of the migrated data object is stored in a backup storage pool if the backup is performed in an incremental backup operation; directing the hierarchical storage manager to recall the migrated data object to the file system if the backup copy of the migrated data object is not stored in the backup storage pool or if the backup is performed in a selective backup operation; creating the backup copy of the migrated data object if the migrated data object is recalled; storing the backup copy of the migrated data object in the backup storage pool if the migrated data object is recalled; creating a backup copy of the stub object if the migrated data object is not recalled; and storing the backup copy of the stub object from the file system in the backup storage pool if the migrated data object is not recalled.