Configuration of a physical control unit to support multiple logical control units for different tape drive types in a mainframe native tape attachment storage system

1. A computer program product for communication between a host and a plurality of tape drives of different types via a single physical control unit (CU), by a processor device, the computer program product embodied on a non-transitory computer-readable storage medium having computer-readable program code portions stored therein, the computer-readable program code portions comprising:

an executable portion that provides a plurality of model types L of tape drives, each said model type being of a different generation, and a number of tape drives QL for each model type;

an executable portion that issues feature codes for a plurality N of logical control units (LCUs) for a customer for the single physical CU;

an executable portion that enters the feature codes into the physical CU to enable configuration of N LCUs;

an executable portion that configures the physical CU to support N LCUs, each LCU supporting communication with a single model type and a maximum of M tape drives;

an executable portion that, based on the number of model types L and the number of tape drives for each model type QL, maps the model types to the N LCUs with priority given in the mapping to the newer generation model types and the model types where QL is greater than M; and

an executable portion that assigns individual tape drives to the LCUs based on model type.

2. The computer program product of claim 1 , wherein the feature codes are an encrypted string that contains information that the code came from a provider of the LCUs and that the customer did in fact legitimately obtain the N LCUs, a serial number of the physical CU and the number of LCUs N obtained by the customer.

3. The computer program product of claim 1 , wherein a point-of-sale (POS) module located in the physical CU or in a remote computer issues the feature codes in response to the customer obtaining the N LCUs.

4. The computer program product of claim 3 , wherein the POS module executes a submodule that process the number of model types L and the number of tape drives QL for each model type and suggest a number of LCUs for a customer that will satisfy a customer specified constraint on the mapping of model types to the LCUs.

5. The computer program product of claim 1 , wherein mapping the model types to the N LCUs ensures that the oldest model type is mapped to at least one LCU.

6. The computer program product of claim 1 , wherein mapping the model types to the N LCUs comprises an executable portion performing the steps of:

if N equals L, mapping each model type to a different one of the LCUs;

if N less than L, mapping the newest model type to a first one of the LCUs, mapping the oldest model type to a second one of the LCUs and mapping the remaining model types newest to oldest to different ones of the LCUs until all the LCUs are mapped; and

if N greater than L, mapping each model type to a different one of the LCUs, mapping model types whose QL is greater than M to another one of the LCUs from newest to oldest model type, and mapping either the newest model type or the model types having the most tape drives per mapped LCU newest to oldest to any remaining LCUs.

7. The computer program product of claim 1 , wherein mapping the model types to the N LCUs comprises an executable portion performing the steps of:

mapping the newest and oldest model types to different LCUs;

if LCUs remain unmapped, mapping model types from newer to older to different LCUs;

if LCUs remain unmapped, mapping the model types whose QL is greater than M to another one of the LCUs from newest to oldest model type; and

if LCUs remain unmapped, mapping either the newest model type to any remaining LCUs or mapping the model types having the most tape drives per mapped LCU from newest to oldest to any remaining LCUs.

8. The computer program product of claim 1 , wherein for model types mapped to more than one LCU, the individual tape drives are assigned to the multiple LCUs based on model type and the number of tape drives QL for that model type to balance the number of drives assigned to each LCU.

9. The computer program product of claim 1 , wherein for model types mapped to more than one LCU, the individual tape drives are assigned to the multiple LCUs based on model type and a physical location of each of the tape drives to distribute drives from the same physical location to different LCUs.

10. The computer program product of claim 1 , wherein the customer connects a tape drive of a different model type to the physical CU changing the number of model types L, and further comprising an executable portion that remaps the model types to the N LCUs based on the new number of model types and reassigns the individual tape drives to the LCUs based on model type.

11. The computer program product of claim 1 , wherein the customer obtains a different plurality N of LCUs, and further comprising an executable portion that reconfigures the physical CU to support the different number of LCUs N, remaps the model types to the N LCUs based on the new number of LCUs and reassigns the individual tape drives to the LCUs based on model type.

12. The computer program product of claim 1 , wherein all of the tape drives for all of the model types are contained in a single library.