CA Dynam for VSE User Guide

Using CA Dynam/T
CA Dynam/T determines which tape is required (either a specific volume for an
input file, or a scratch tape for an output file) and searches all available tape
drives for the tape. A tape drive is considered available if all of the following
conditions are satisfied:
• The unit is in DVCUP status.
• The unit is not assigned to any logical unit in any partition, either through
a temporary or standard assignment.
• The unit is a member of a defined POOL of tape drives available for the
CPU and partition issuing the OPEN (see DTPOOL option record), or no
tape drive pools have been defined in the DTPOOL option record.
• The unit is not locked against cross-CPU use by CA Dynam/T (see DTLOCK
option record).
• The unit is physically accessible (has not been DETACHed under VM, or has
not been placed offline).
• The unit is ready and contains a tape that is at load point.
• The tape on the unit has a recording density compatible with the tape
drive, and no I/O errors occur when the VOL1/HDR1 labels are read.
• The tape unit is of the same type as the tape currently being opened.
If all of the above conditions are met, CA Dynam/T reads the tape on the unit
to determine if it is the desired volume. Depending on whether it is the desired
volume, CA Dynam/T does the following:
• If it is the desired volume, the assignment is made, and a message is
issued to the operator informing him of the volume, data set name, logical
unit, and selected tape drive.
• If it is not the desired volume, the tape is returned to load point and
CA Dynam/T continues searching until all available tape units defined in
the applicable DTPOOL table have been searched. If no DTPOOL option
records are defined, the search continues through all tape drives in the
PUB table. If the correct volume has not been located, CA Dynam/T
instructs the operator to mount the desired volume (input) or a scratch
volume (output). When the operator responds, CA Dynam/T is again
activated and processing continues.
Chapter 2: Maintaining Tape Files 2–13