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) 

## 7.12 Preserving file system objects on tape 

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: 

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 

The following items are not written and read to and from tapes: 

GLYPH<SM590000> Timestamps 

GLYPH<SM590000> User ID and group ID 

GLYPH<SM590000> ACLs 

To save these file system objects on tape, you have two options: 

GLYPH<SM590000> Calling the ltfseesave  command directly with a scan list file 

GLYPH<SM590000> An IBM Spectrum Scale policy with the mmapplypolicy  command 

## 7.12.1 Saving file system objects with the ltfsee save command 

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> . 

