Whenever an object exists on tape, OAM can retrieve the object only when a device compatible with the format of the data written on the tape volume is available at the time of the retrieve request. To retrieve any objects from tape, you must initialize OAM with a valid CBROAMxx specification.

If an Object or Object Backup storage group that used to have its objects written on tape is now having objects written to optical media, those objects can also be read back using a tape device compatible with the format of the data written on the tape volume available at the time of the retrieval request. To read data back from tapes previously written in a group that is no longer writing data to tape, there does not have to be a SETOAM statement for that group in the CBROAMxx PARMLIB member processed.

OAM has a default of one system read and one system write task; each group has a default of one read task and one write task. The installation should ensure that there is a compatible tape device available for allocation at the time the retrieval request is received. If there is no device available for allocation, z/OS allocation recovery issues allocation recovery messages, requesting that an offline or inaccessible device be made available. If this is not possible, the retrieval request for the pending mount fails.

Related reading: For more information, see Using dynamic allocation for tape drives.