Recycle processing separates valid and invalid data sets and consolidates valid data sets on fewer tapes, therefore making more scratch tapes available for reuse. Figure 1, Figure 2, and Figure 3 illustrate the concept of recycle processing:

Figure 1. Creation of Tape Data Set Copies. DFSMShsm makes an entry in the offline control data set record for each data set stored on a migration or backup tape.

Figure 2. Tape Data Set Copy Invalidation. As migrated data sets are recalled and as backup versions expire, the data set entries in the OCDS become invalid. Invalid data sets remain on the tape, however, until the tape is recycled.

Figure 3. Tape Efficiency Through Recycle Processing. As a result of recycle processing, valid data sets from source tape 1 are copied to the recycle target tape. After all valid data sets from source tape 1 are copied, valid data sets from source tape 2 are copied to any recycle target tapes. Source tapes that have been recycled are returned to the scratch pool.

You can choose to run recycle on a regular schedule or you can choose to wait until DFSMShsm uses enough tapes that you need to make more tapes available. Because recycle can be run independently for migration tapes and for backup tapes, the schedules can be independent of each other. Because recycle is operating only on DFSMShsm-owned volumes, you can schedule it whenever your tape devices are available.