Date: Mon, 20 Jul 2009 05:53:55 -0700 (PDT) From: Richard Mahlerwein <mahlerrd@yahoo.com> To: freebsd-questions@freebsd.org Subject: Re: Odd behavior after installing a tape drive Message-ID: <829991.56927.qm@web51007.mail.re2.yahoo.com>
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> From: Polytropon <freebsd@edvax.de>=0A> Subject: Re: Odd behavior after i= nstalling a tape drive=0A> To: "Tim Judd" <tajudd@gmail.com>=0A> Cc: mahler= rd@yahoo.com, freebsd-questions@freebsd.org=0A> Date: Monday, July 20, 2009= , 12:22 AM=0A> On Sun, 19 Jul 2009 21:43:29 -0600,=0A> Tim Judd <tajudd@gma= il.com>=0A> wrote:=0A> > I'm no expert on tape drives either, but I was sur= e=0A> that "losing a=0A> > SCSI device" is a bad thing for SCSI -- think of= it as=0A> an IDE drive.=0A> > you don't just go pulling power or data from= a=0A> running, booted=0A> > computer.=0A> =0A> With SCSI, "hot plug" is us= ually not that problematic as=0A> with=0A> "modern" ATA and SATA on the PC.= Anyway, using=0A> =0A> =A0=A0=A0 # camcontrol stop <unit>=0A> =0A> before = switching off or detaching a SCSI component is often=0A> a=0A> good idea.= =0A> =0A> =0A> =0A> > All the devices in a computer are on, stays on, until= =0A> the system shuts down.=0A> =0A> SCSI allows you to have "internal devi= ces" outside the=0A> computer,=0A> connected with a cable. In principle, it= doesn't even=0A> matter if=0A> a hard disk is inside the computer or outsi= de, same for=0A> optical=0A> disc drives, tape drives, and even scanners. "= Hot plug" has=0A> always=0A> been a nice feature of SCSI, even 10 or more y= ears ago,=0A> where=0A> you couldn't imagine something similar in the PC wo= rld.=0A> =0A> =0A> =0A> > The PTY/SCSI subject of your email should be=0A> = unrelated, but a abruptly=0A> > missing device is never a positive outcome = for an=0A> OS.=A0 Think about the=0A> > old "removing a mounted USB drive = =3D panic" issue we've=0A> dealt with for=0A> > years.=0A> =0A> Or /dev/mem= : device disappeared. :-)=0A> =0A> =0A> =0A> > I am questioning your reason= ing behind turning off a=0A> tape drive on a=0A> > live system.=A0 I would = never recommend that.=0A> =0A> As I said, if you do it "the SCSI way", it's= completely=0A> unproblematic.=0A> =0A> =0A> =0A> =0A> -- =0A> Polytropon= =0A> From Magdeburg, Germany=0A> Happy FreeBSD user since 4.0=0A> Andra moi= ennepe, Mousa, ...=0A> =0A=0AThanks! I'll do that in the future - I was g= etting the idea that since camcontrol *includes* a "stop" command I should = have done that before pulling the power anyway. :)=0A=0AI 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 moo= n.=0A=0AI'll have a bit of time this week to test taking it down and back u= p a few times the "correct" way and see if it exhibits any of the same beha= vior. =0A=0AThanks again!=0A=0A-Rich=0A=0A=0A=0A
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