Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!cse!texas!harrison
From: harrison@csl.dl.nec.com (Mark Harrison)
Newsgroups: comp.unix.admin
Subject: Unhooking scsi devices while machine is running
Message-ID: <1991May24.143831.10687@csl.dl.nec.com>
Date: 24 May 91 14:38:31 GMT
Organization: NEC America, C & C Software Development Laboratory
Lines: 37

We have a portable scsi qic-150 tape drive that we share among
several users.  We basically use it when we have some installs
or private backups and want to do the work at our desks instead
of standing in the machine room.

Most of this is done on diskless workstations (Sun SLC's), and we
freely plug and unplug the tape drive.

There has been some concern over a regular workstation (Sparc 1+)
that has an additional external scsi hard disk.  For some reason,
we are under the impression that to hook the tape drive to that
machine, we have to bring the machine down, unhook the disk drive,
plug the tape drive to the machine, and then daisy-chain the disk
drive to the tape drive.  I think whoever came out and installed
the thing had it set up that way, and nobody (including me :-)
wants to take the blame for screwing things by trying it differently.

My questions:

1.  Is there *any* significance to the order of daisy chaining?

2.  Is it safe to plug and unplug the tape drive while the system
    is up?

3.  (this is the point of the whole posting)  Will I screw things
    up if I simply plug and unplug the tape drive into the disk
    drive while the system is running?

4.  What FM should I be reading to know about this stuff?

Thanks in advance,
Mark.
-- 
Mark Harrison           | Note: harrison@ssd.dl.nec.com and
harrison@csl.dl.nec.com | necssd!harrison are not operating at
(214)518-5050           | present.  Please forward mail through the
                        | above address.  Sorry for the inconvenience.