Subject: Re: scsi tape changer / st_unmount interaction.
To: None <>
From: Martin J. Laubach <>
List: tech-kern
Date: 03/20/1999 23:03:55
| 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):

  Ah, that explains what I have been observing: after a dump on the
non rewinding device, my Exabyte will refuse to eject the tape on
manual request (pressing the eject button on the front panel).

  Up till now I thought it is just a weirdness of the Exa...

| I'm not quite sure what the right answer is here..

  I can see the idea behind this behaviour, kind of, in that one
should only get tapes in a "known state" (ie. rewound) out of the
tape drive. On the other hand, all DAT and 8mm tapes rewind the
tape anyway when one ejects it.

| My best guess is that doing an st_unmount(st, NOEJECT) in stclose()
| when the tape's at BOT would be an improvement over the current
| situation.

  Well it would not really change much, since to get the tape to
BOT means I need to get it to rewind, which means I need to use
mt to rewind... and then I can do a "mt offline" anyways.

| Anyone with more SCSI clue have any opinions on the Right Thing To Do
| here?

  Not really sure, but I personally would prefer the device not
to mess with the lock status. If I want to make sure nobody ejects
a tape, I think a command like "mt lock" would be appropriate.