Execution of a mount request

You can issue the SECURE-RESOURCE-ALLOCATION command (see the “Commands” manuals [3]) when using the NDM device management system to reserve specific tape devices of storage locations. These locations must be the same as those from which the tapes are also selected for processing.
If you then wish to have a particular tape, e.g. the tape TAPE01, mounted on one of these devices. The figure 8 shows the sequence of operations involved in such a mount request. The mount request can be initiated, for example, by means of an ARCHIVE statement.

Figure 8: Sequence of operations for a mount request

The device management system reacts to this request as follows:

• Location definition for the tape
  NDM ascertains via MAREN the location to which this VSN is allocated. If the VSN has been entered in the MAREN catalog, the associated location is used. Otherwise, MAREN returns a location determined via the MAREN exit routine or a default location.

• Device selection from a storage location
  NDM uses the location returned by MAREN for the subsequent mount job. NDM selects a suitable free device at the location.
  The location returned by MAREN is mandatory for NDM if it was made known to NDM using ADD-DEVICE-DEPOT. If NDM does not know the location, it accesses a device from those which have not been allocated to a location.