I have a question regarding "ownership" of a tape address when more than
one system has access to the control unit. It is my understanding that
since the time of the 3480 control unit, a switch or electronic latch is
set in the CU when an address is ATTACHed (VM) or ALLOCated (MVS) and that
the latch prevents another system from attaching or allocating that same
address. When the address is freed by being detached from the id on VM or
unallocated on MVS, the latch is immediately reset indicating that the
address is available. Am I correct in the above.
We occasionally see situations between or VM lpars and MVS lpars where an
address has been detached from VM but is not available on MVS. It is DFSMS
on MVS that is trying to allocate the address. If a CP Q TA is issued on
VM, and the reply is "An active tape was not found" is there any way that
the VM lpar could still own an address?
Jim
Jim Bohnsack
Cornell Univ.
(607) 255-1760
