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Date: Mon, 30 Jun 2003 17:51:50 +0000
From: "Sergey \"DoubleF\" Zaharchenko" <doublef@tele-kom.ru>
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To: Rob Lahaye <lahaye@snu.ac.kr>
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Subject: 
 Re: mount & umount read-only floppy: unmount failed: Input/output
 error ??
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Rob Lahaye wrote:
> I created the installation floppy from "kern.flp". Removed it from the
> drive, to make it read-only.
> I then put it back into the drive and do, as root:
> 
> # mount -t ufs /dev/fd0 /mnt
> # umount /dev/fd0
> umount: unmount of /mnt failed: Input/output error

You know, ufs filesystems store the "last mounted on" string in 
themselves (it is reported by "fsck", f.e.). I am not sure, but it seems 
like mount is willing to write it to the floppy.

 > Perhaps the updates from mounting the floppy aren't being written
 > out to the actual media until you try to unmount it - some kind of
 > caching issue?

So you were _writing_ to a read-only floppy;)? Yes, of course, FreeBSD 
does cache them (that's why you can't take it out without unmounting). 
It's just that, short of trying to write to the floppy, you can't get to 
know it's read-only AFAIK.

HTH,
				DoubleF