Host Ignores Scratch Tapes Mounted on the MAS

Symptom

Following a request for a scratch tape, the MAS selects a volume from its scratch pool and mounts the tape on a virtual tape drive. However, the mainframe never uses the volume mounted on the MAS.

Resolution

One possible explanation for this is that the range of scratch tapes defined on the MAS does not match what is defined on the mainframe.

For example, say the MAS had scratch tapes CX0000 through CX9999 defined, but the mainframe tape management system was only told that volumes CX0000 through CX0100 were scratch tapes. The first 101 scratch requests would be satisfied with tapes that were known to the host and all would be well. From then on, the MAS would allocate and mount scratch volumes that were not scratches from the host's point of view.

The consequences will vary depending on the host operating system and/or tape manager. One likely scenario is that the host would simply ignore the "unknown" tape that the MAS mounted and wait for a tape that it recognizes. Possibly, the host will simply unload the "unknown" tape.

In either case, the original scratch mount request will not have been satisfied by the volume mounted by the MAS. The solution is to make sure that exactly the same range of volumes is defined on both the MAS and the host.