Re: Stale mount on disconnected device: how to delete it?

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On Tue, Dec 18, 2007 at 01:13:55AM +0100, Romain Tartière wrote:
On Mon, Dec 17, 2007 at 10:32:48AM -0800, Yuri wrote :
In case of USB device (which device in question in this problem
happens to be) usbd can be used to mount it.

If attach/detach events trigger mount/unmount commands this problem
shouldn't exist. I didn't try though.

The problem is that the detach event can be caught only too late to
unmount the device properly. How may it be possible to sync a disk
``as soon as it is detached'' (that is when it is not physically
connected to the computer anymore)? Mounting the disk read-only may
be a workaround, just as not caching writes (default behaviour of some
versions of Windows) and syncing the disk all the time, but this is
not as reliable as the mount system provided by Unix and Unix like
operating systems.

AFAICR, this is the sole weakness of the FreeBSD operating system I
know :) And since it is, according to me, an operator error, the best
we can do is to use the system as it was designed for ;)

Off the top of my head, what is wrong/hard with just logging a device
failure, discarding all remaining cached operations, and unmounting the
fs when a disk device goes missing? I understand that this is not a
viable solution for critical filesystems, but I can see nothing wrong
with this approach for removable devices and/or non-critical fs's.

Just my $0.02.

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