HP NonStop G-Series - Manual (Page 116)

Tape Library Control Path Configuration Guidelines
DSM/Tape Catalog User’s Guide — 520233-008
7 - 8
Control Path Flow Description
ten attempts, none of the alternate selected tape volumes can be found in
a tape library.

If no tape volume is specified in a TAPE DEFINE request

If a tape drive that is not in a tape library is specified.
4. $ZSVR sends a message to obtain a list of tape drives in order of proximity
(number of passthroughs needed) to the specified tape volume.
$ZSVR finds the closest available tape drive in the tape library. If all tape drives are
busy, $ZSVR generates an EMS event and queues the request. $ZSVR delays this
tape request for three minutes and then restarts this step.
5. $ZSVR sends a request for the specified tape volume to be mounted on the
specified tape drive.
6. The tape cartridge being loaded sends an ATTENTION INTERRUPT message to
the tape process via the DATA path.
7. The tape process performs AVR and informs $ZSVR about the mounted tape
cartridge.

If the internal and external tape volume labels do not match, the OPEN fails,
and the tape cartridge is ejected from the tape library by $ZSVR.

If the labels match, but the tape volume has the wrong label type, the OPEN
fails, and the tape cartridge is returned to a cell.
8. $ZSVR replies to the file system with the name of the tape drive to use.
9. The file system connects the application with the tape drive, and the OPEN
completes. The application is now connected through the DATA path.
At each tape volume switch, or when the application closes the tape drive and the
tape cartridge is unloaded, $ZSVR sends a dismount message to the tape library
to remove the tape cartridge from the tape drive and return it to a cell.