When considering which functions to process in a tape library, think in terms of space-management processing, availability-management processing, or control data set backup processing as indicated in the following implementation scenarios.

As you review these scenarios, notice that the migration and backup conversions are implemented differently. The implementations contrast each other because, for migration, existing tapes are inserted into the library and for backup, scratch tapes are inserted into the library and the existing backup tapes are left in shelf storage. There is no requirement to convert in this manner, but the different methods are shown as examples of the different ways to convert to an SMS-managed tape library.

The DFSMShsm ARCTEEXT exit supports SMS tape library management so that not all tapes for a given DFSMShsm function are required to be located either inside or outside a library. The ARCTEEXT (Tape Ejected) exit provides the capability of dynamically inserting nonlibrary-resident DFSMShsm migration, backup, and dump tapes as they are needed for input. This capability enables a customer to use a smaller automatic library and still have the choice of either allocating tape volumes outside the library or dynamically reinserting tapes whenever ejected tapes are needed. This action can be done without failing jobs or adversely affecting other DFSMShsm activity. The ARCTEEXT exit gains control at a point before code supporting the TAPEINPUTPROMPT function is processed as well as before tape allocation is required.