Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!tut.cis.ohio-state.edu!ucbvax!ucsd!hub!casaba!dz
From: dz@casaba.ucsb.edu (Daniel James Zerkle)
Newsgroups: comp.sys.next
Subject: Re: Optical disk problem
Keywords: system software, mounting disks
Message-ID: <2172@hub.UUCP>
Date: 4 Aug 89 17:30:52 GMT
References: <5741@pt.cs.cmu.edu>
Sender: news@hub.UUCP
Reply-To: dz@cornu.ucsb.edu  (Daniel James Zerkle)
Organization: University of California, Santa Barbara
Lines: 64

In article <5741@pt.cs.cmu.edu> rwb@vi.ri.cmu.edu (Bob Berger) writes:
>I'm having lots of problems using the optical disks. My latest
>problem occurred when I inserted a disk while I was still logging in.
>The machine mounted the disk at some unknown place in the file system.
>Even after power cycling the machine, it insists that this disk is mounted
>on volume 0. However, I cannot find a directory entry for it to use with
>the unmount command in the browser.

You've disk-covered yet another annoying bug in the 0.9 release.
Sometimes the autodiskmount command will utterly flake out, and
you have to do things manually (probably as root).

The first thing to try is the simple "/etc/mount" command (you do not
have to be root to do this).  This will report what disks are mounted
where.  The optical disk is /dev/od0a and the hard disk is /dev/sd0a.

One thing that works to get a stuck disk out without su'ing to root
is to use the "mount" command from the window manager (browser).
This will often spit the disk out and ask you to put in another or
press "n" to cancel.  Pressing "n" can cause infinite problems
(another bug), so be careful.

If the mount command did not report an optical drive, you will never
find the directory where it is mounted, because it isn't.  You will
have to get it mounted yourself.  As root, type something like:

# mount /dev/od0a /opt

which will mount the disk on /opt.

If you want to get the disk out, first make sure it is not mounted.
(Using eject from the window manager is fine under normal circum-
stances, but you MUST re-insert the disk and unmount it later, before
logging out, or all Hell breaks loose.  Better to always unmount a
disk before ejecting it, if you can.)  You can manually unmount the
disk (as root, probably), with

# umount /opt

which will unmount any disk mounted on /opt.  Not that if any program
has files open on the disk, or even has a current directory there
(including csh and WM 28), this won't work.  Disk twiddling is best
done with nobody around and just one terminal or shell window.
As root, you can manually eject the disk with:

# disk -e /dev/rod0a

After this, you can try just popping the disk back into the drive,
in hopes that it will end up automounted in your home directory.
Hopefully, these leftover bugs will be cleaned up by release 1.0.

In case you hadn't figured it out on your own, the root password
will let you unmount the disk from a user's home directory, and
mount it somewhere else, where it will not be ejected when the
user logs out.  It will just stay there until it gets unmounted
and ejected.  This avoids the usual automount problems, although
it means that ordinary users can not use their own disks.  The best
way to avoid bugs is to never, NEVER press the 'n' key when you are
requested to insert a disk (especially one that is already mounted,
but merely ejected), unless you really have to do it.
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