Label question...why does ufs label vanish on mount?

[Jeremy Chadwick]

On Wed, Oct 13, 2010 at 08:29:06AM +0200, Stefan Bethke wrote:
> Am 13.10.2010 um 06:56 schrieb Andrey V. Elsukov:
> 
> > On 12.10.2010 22:51, Kevin Oberman wrote:
> >> For some reason the /dev/ufs/label entry that geom creates for every UFS
> >> formatted partition is deleted when the device is mounted. This is not
> >> the case for other file systems, though I have not tried them all. It
> >> makes the drive much harder to deal with when you have to keep track of
> >> which physical drive contains the labeled media. It is a particular
> >> issue for hald and the tools which depend on it.
> >> 
> >> Is there a good reason for this odd behavior of UFS? If there is not a
> >> good reason, could it be changed?
> > 
> > When you are opening provider for writing (i.e. mount FS) GEOM(4)
> > initiates SPOILING and all consumers that are attached to this provider
> > except one will self-destroyed. When you are closing provider GEOM(4)
> > initiates TASTING and consumers can return back. Look at man 4 geom
> > for details.
> 
> That explains the mechanism, but not the rationale.  Or is it just an unintended consequence?  And how is da2p1 different from ufs/mylabel?  (Mount da2p1 and ufs/mylabel is removed, but not the other way around.)

Pulling in pjd@ who can probably shed some light on this.

Pawel, you might be interested in this part of the thread specifically:

http://lists.freebsd.org/pipermail/freebsd-stable/2010-October/059483.html

-- 
| Jeremy Chadwick                                   jdc at parodius.com |
| Parodius Networking                       http://www.parodius.com/ |
| UNIX Systems Administrator                  Mountain View, CA, USA |
| Making life hard for others since 1977.              PGP: 4BD6C0CB |