Then, it continues by premigrating all files that are larger than 5 MB: RULE 'premig3' MIGRATE FROM POOL 'system' THRESHOLD (0,30,0) TO POOL 'ltfs' WHERE( AND (KB_ALLOCATED > 5120)) The rule in the following example is the preferred rule when performing premigrations only. It  requires a callback to perform the stubbing. If the storage pools occupancy is below 100%, it  selects all files larger than 5 MB for premigration. If you set the threshold to 100% the storage  pools occupancy will never exceed this value, and so migrations will not be performed. In this  case, a callback is needed to run the stubbing. For an example of a callback, see 8.10.2,  “Creating active archive system policies” on page 236. RULE ‘premig4’ MIGRATE FROM POOL ‘system’ THRESHOLD (0,100,0) TO POOL ‘ltfs’ WHERE  (FILE_SIZE > 5242880) Symbolic links, empty regular files, and empty directories are some file system objects that do  not contain data or content. When you save these types of file system objects, you cannot use  migration  and  premigration  commands. HSM is used to move data to and from tapes, that  is, for space management.  Because these file system objects do not have data, they cannot be processed by migration  or premigration. A new driver (called the  save driver ) was introduced to save these file system  objects to tape. The following items (data and metadata that is associated with an object) are written and read  to and from tapes: The following items are not written and read to and from tapes: To save these file system objects on tape, you have two options: The  ltfsee save  command is used to save symbolic links, empty regular files, and empty  directories to tape. The command syntax is the same as the  ltfsee migrate  or  ltfsee  premigrate  commands. The following is the syntax of the  ltfsee save  command: ltfsee save -s <GPFS scan list file> -p <target tape cartridge pool 1> <target  tape cartridge pool 2> <target tape cartridge pool 3> The  <GPFS scan list file>  file includes the list of file system objects (symbolic links, empty  regular files, and empty directories) to be saved. Each line of this file must end with  -- <full  path file system object name> .  7.12.1 Saving file system objects with the ltfsee save command 7.12 Preserving file system objects on tape GLYPH<SM590000> File data for non-empty regular files GLYPH<SM590000> Path and file name for all objects GLYPH<SM590000> Target symbolic name only for symbolic links GLYPH<SM590000> User-defined extended attributes for all objects except symbolic links GLYPH<SM590000> Timestamps GLYPH<SM590000> User ID and group ID GLYPH<SM590000> ACLs GLYPH<SM590000> Calling the  ltfseesave  command directly with a scan list file GLYPH<SM590000> An IBM Spectrum Scale policy with the  mmapplypolicy  command Chapter 7. Operations  179