The ATLDS and the MTL may be shared among multiple systems and, in some cases, among multiple SMS complexes. In all cases, it is the responsibility of the installation to ensure that an individual library-resident tape drive not be allocated by two systems concurrently. This means that the tape drive can be online to only one SMS complex. In addition, if the SMS complex where the tape drive is online does not have JES3 or equivalent support for the sharing of tape drives, the tape drive can be online to only one system. To ensure that volumes intended for VM use are not made available to SMS, the installation should assign a recognizable volume serial number range to VM and a different range to SMS. The cartridge entry installation exit, through use of the ignore return code, prevents SMS from using the wrong set of volumes. See Figure 1 for an example of sharing a tape library among systems.
- There must be a single shared tape configuration database among all systems in all SMS complexes. This means there is one general volume catalog, and at the most one specific volume catalog for each valid initial volser character.
- The library name associated with the hardware library ID must be the same in each SCDS. The library console name and the scratch volume message thresholds must also be the same. The entry default data class, entry default use attribute, eject default, and system connectivity status can be different in each SCDS.
- There is a single pool of scratch volumes to be shared among all the SMS complexes. This pool consists of separate library manager categories for each of the supported media types.