Odd behavior after installing a tape drive
mahlerrd at yahoo.com
Mon Jul 20 12:53:57 UTC 2009
> From: Polytropon <freebsd at edvax.de>
> Subject: Re: Odd behavior after installing a tape drive
> To: "Tim Judd" <tajudd at gmail.com>
> Cc: mahlerrd at yahoo.com, freebsd-questions at freebsd.org
> Date: Monday, July 20, 2009, 12:22 AM
> On Sun, 19 Jul 2009 21:43:29 -0600,
> Tim Judd <tajudd at gmail.com>
> > I'm no expert on tape drives either, but I was sure
> that "losing a
> > SCSI device" is a bad thing for SCSI -- think of it as
> an IDE drive.
> > you don't just go pulling power or data from a
> running, booted
> > computer.
> With SCSI, "hot plug" is usually not that problematic as
> "modern" ATA and SATA on the PC. Anyway, using
> # camcontrol stop <unit>
> before switching off or detaching a SCSI component is often
> good idea.
> > All the devices in a computer are on, stays on, until
> the system shuts down.
> SCSI allows you to have "internal devices" outside the
> connected with a cable. In principle, it doesn't even
> matter if
> a hard disk is inside the computer or outside, same for
> disc drives, tape drives, and even scanners. "Hot plug" has
> been a nice feature of SCSI, even 10 or more years ago,
> you couldn't imagine something similar in the PC world.
> > The PTY/SCSI subject of your email should be
> unrelated, but a abruptly
> > missing device is never a positive outcome for an
> OS. Think about the
> > old "removing a mounted USB drive = panic" issue we've
> dealt with for
> > years.
> Or /dev/mem: device disappeared. :-)
> > I am questioning your reasoning behind turning off a
> tape drive on a
> > live system. I would never recommend that.
> As I said, if you do it "the SCSI way", it's completely
> From Magdeburg, Germany
> Happy FreeBSD user since 4.0
> Andra moi ennepe, Mousa, ...
Thanks! I'll do that in the future - I was getting the idea that since camcontrol *includes* a "stop" command I should have done that before pulling the power anyway. :)
I still don't know if the two items were related in any way, but I'm not really that worried about it unless it happens again - or at least more than once in a blue moon.
I'll have a bit of time this week to test taking it down and back up a few times the "correct" way and see if it exhibits any of the same behavior.
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