When you share an automated tape library between DFSMS and BTLS, there are restrictions on the sharing of volumes between the systems. For example, although a private volume is defined in the TCDB on DFSMS, it cannot be shared unless it is also defined in the BTLS catalog.

Consider partitioning the automated tape library using some volumes under DFSMS and other volumes under BTLS. This is important when you plan to use scratch volumes. Volumes that are part of scratch pools cannot be effectively shared.

Only volumes that are long-term private volumes can be shared effectively. You can define each private volume to both systems, but if the volume changes status, it is likely that the BTLS catalog and the TCDB will not match the volume status defined in the DFSMSrmm control data set. You can modify the CBRUXENT exit supplied with DFSMSrmm to force the Library Control System to not process the volumes intended for BTLS management.

If you want to designate specific scratch volumes for use on DFSMS and others for use with BTLS:

1. Modify the DFSMSrmm supplied CBRUXENT exit by setting the return code to 12 (UXEIGNOR) for all volumes that are to be managed by BTLS.
2. Use the AMS LIBRARY SETCATEGORY command to set the appropriate BTLS private or scratch category for all volumes entering the automated tape library that are ignored by the Library Control System.

If you modify the CBRUXENT exit, issue a WTO that you trap in Netview or equivalent. Use this event to trigger the start of the AMS LIBRARY SETCATEGORY command on the system where BTLS resides.

An easier implementation would be possible using separate control data sets, one for DFSMSrmm with system-managed tapes, and one for DFSMSrmm with BTLS volumes. The disadvantage of this is extra administration and total segregation of volumes.