topic Re: Tape loading in Operating System - OpenVMS

Tape loading

Ian Miller. — Fri, 14 Jul 2006 04:55:37 GMT

Is there a SCSI command that can be sent to a TZ87/8/9 tape drive to load a tape which is physically present but not loaded?

I know that the PACKACK IO function can be used to detect that a tape is present. Does this show a tape is loaded and ready to mount or just that a tape is present?

I will do some experiments with SCSI_INFO to see what can be found.

Re: Tape loading

Ian Miller. — Fri, 14 Jul 2006 05:52:38 GMT

Intrigingly when SCSI_INFO says its doing a Start Unit then if a tape is present but not loaded then the tape is loaded!

Now I wonder what IO function code SCSI_INFO is doing when it says its doing start unit.

Re: Tape loading

Volker Halle — Fri, 14 Jul 2006 06:06:52 GMT

Ian,

SCSI_INFO is using an IO$_DIAGNOSE QIO to send a START_STOP_UNIT_OPCODE (0x1B) with a couple of additional bytes...

Source listings: [SCSI]SCSI_INFO

Volker.

Re: Tape loading

Jim_McKinney — Fri, 14 Jul 2006 06:16:21 GMT

SCSI_INFO uses a $QIO with an IO$_DIAGNOSE function code. For the SCSI start and stop unit operations P1 is a descriptor that points to a command data buffer where the SCSI operation code is x1B, and, P2 is the length of that buffer.

Re: Tape loading

Ian Miller. — Fri, 14 Jul 2006 09:35:10 GMT

The results of tests of doing commands similar to

$MCR SYS$ETC:SCSI_INFO MKA400 NL:

to load tapes on various drives

TK50 no
TZ30 yes if the handle is over to the right.
TZ87 yes
TZ88 yes