Recommendations for using DFSMSrmm and DFSMShsm

Related reading: See z/OS DFSMShsm Implementation and Customization Guide for details on DFSMShsm data set naming formats.

Follow these guidelines when running DFSMSrmm with DFSMShsm:

Run DFSMShsm with scratch tapes that DFSMSrmm manages so you can have a single scratch pool for all users of tape and so you can gain any benefits available from pre-mounting of scratch tapes in cartridge loaders.
Use RACF TAPEVOL or DATASET profiles to ensure tape data security on your system.
Set these suggested DFSMShsm system option parameters.
```
SETSYS EXITOFF(ARCTVEXT) -
       SELECTVOLUME(SCRATCH) -
       TAPEDELETION(SCRATCH) -
       TAPESECURITY(RACF) -
       PARTIALTAPE(MARKFULL)
```
Specify EXITOFF(ARCTVEXT) if DFSMSrmm is your only tape management product because DFSMShsm always calls the DFSMSrmm programming interface EDGTVEXT.

Specify SELECTVOLUME(SCRATCH) to cause DFSMShsm to issue a nonspecific mount request for output tapes which can be satisfied by any empty tape acceptable to both DFSMShsm and DFSMSrmm.
Specify PARTIALTAPE(MARKFULL):
- If you are using automatic cartridge loaders so DFSMShsm marks partially used volumes as full. This allows the first output tape of each task to be a nonspecific mount, which means that you get faster tape mounts. You can specify migration and backup options separately.
- If you want to get migration and backup data duplicated and moved to a storage location in a timely manner. Marking the tapes full prevents a task's last tape, that is only partially filled, from remaining in the library an additional 24 hours before being duplicated the next day for disaster protection.
- If you use TAPECOPY or the DUPLEX tape feature to duplicate tapes and ship them to a storage location, use MARKFULL to end one day's cycle and begin another day's cycle. TAPECOPY only processes full volumes which means that the original tapes have no copy until they are full. This means that a copy might not be available at the storage location as quickly as expected. Using the DUPLEX tape feature means that both the original and copy tapes are created at the same time. DFSMSrmm ships the DUPLEX copy to the storage location as quickly as possible. This might create problems if DFSMShsm expects to continue the writing to the tape the next day. Marking the DUPLEX tapes full allows DFSMSrmm to process both TAPECOPY copies and DUPLEX tapes in the same way.
Set these suggested dump definitions:
```
DEFINE DUMPCLASS(class -
       AUTOREUSE -
       RETENTIONPERIOD(days))
```
Use RETENTIONPERIOD instead of TAPEEXPIRATIONDATE to allow the tapes to be reused or written to by any other program without their needing to be reinitialized after DFSMShsm expires them.

Use AUTOREUSE to have the tapes returned to a scratch pool as soon as the data on the tape are invalidated. This option is necessary for DFSMShsm to call DFSMSrmm to release the tape volume. Without AUTOREUSE, a DELVOL command must be issued for each tape after it is returned to the locale of the tape drives.

Do not use AUTOREUSE for a DFSMShsm-managed pool when also removing tapes from the vicinity of the tape drives. This is because DFSMShsm might select a remotely located tape before DFSMSrmm is able to cause the tape's physical return to the locale of the tape drives.