Esoteric name tape drive restriction

When IMS log archive JCL specifies an esoteric name in the UNIT= parameter, the tape addresses to be used are defined by the definition of that name in the HCD (hardware configuration definition).

The specified esoteric name is used to search for eligible devices and the device type is recorded to the RECON for each LOG data set. Device type is an IBM®-supplied name that identifies a device by its machine type and model. For example: 3480 or 3400-5.

When IMS Database Recovery Facility dynamically allocates a cataloged data set, the device type is used for allocation. The set of devices defined for this device type name can be fewer or more devices than the set described by the original esoteric name.

For example, if the esoteric name LOGTAPES includes just the five 3490 device addresses 3B0-3B4, LOGTAPES will be searched and the resulting device type 3490 is recorded in the RECON. Device type 3490 can include many more devices than just 3B0-3B4.

When these archived logs are specified to IMS Database Recovery Facility for use in the recovery process, other similar tape device addresses might be called for in the mount requests. Allocation with UNIT=3490 will select available 3490 units that might or might not be within the LOGTAPES esoteric group.