Subject: Re: scsi tape changer / st_unmount interaction.
To: Bill Sommerfeld <>
From: Wilko Bulte <>
List: tech-kern
Date: 03/20/1999 21:59:10
As Bill Sommerfeld scribbled...
> I've been playing with a Sony TSL-9000 tape changer.
> It has the following interesting behavior:
>  - when the tape drive has the "prevent media removal" bit set,
> changer commands which attempt to move things into/out of the drive
> fail.
>  - when the tape drive is given an EJECT command (either via the
> "eject" command or by mt rewoffl), the changer catches the eject and
> *loads the next tape in sequence*.
> This interacts poorly with the no-rewind tape device, which sets
> "prevent media removal" on open(), and leaves it set on close, as this
> sequence (which works with other changers i'm familiar with):
> 	    chio move slot 2 drive 0
> 	    <dump to /dev/nrst0>
> 	    mt rewind
> 	    chio move drive 0 slot 2
> causes the `chio' to fail.  Changing `mt rewind' to `mt rewoffl'
> causes the subsequent chio to fail for a different reason: the eject
> done by mtrewoffl causes the loaded tape to be ejected into slot 2,
> and the tape from slot 3 is loaded in its place..

Smells like something I've seen on a DLT loader. That one was
in sequential loading mode (i.e. it loaded the next tape as soon as
the previous one was unloaded) _unless_ one sent it a specific SCSI
mediachanger command. The alternative was to flip a bit in a vendor
unique mode page (DisLdrAutomatic or something like that).

Groeten / Cheers,
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