Cannot create 2nd gmirror

[Janos Dohanics]

On Fri, 6 Jan 2012 11:55:50 +1030
William Brown <william.e.brown at adelaide.edu.au> wrote:

> > 
> > I am trying to add a second gmirror, gm1:
> > 
> > # sysctl kern.geom.debugflags=16
> > kern.geom.debugflags: 16 -> 16
> > 
> > # gmirror label -v -b round-robin gm1 /dev/ad4
> > Metadata value stored on /dev/ad4.
> > Done.
> > 
> > # gmirror insert gm1 /dev/ad6
> > gmirror: No such device: gm1.
> > 
> > Why does gm1 fail to be created?
> > 
> 
> What is the output of gmirror list after you run the gmirror label? 
> 
> Alternately, according to
> http://www.freebsd.org/cgi/man.cgi?query=gmirror&apropos=0&sektion=0&manpath=FreeBSD+6.1-RELEASE&format=html
> you should be able to just run 
> 
> gmirror label -v -b round-robin gm1 /dev/ad4 /dev/ad6
> gmirror rebuild gm1 /dev/ad6
> 
> 
> Sincerely,
> 
> William Brown
> 
> Research & Teaching, Technology Services
> The University of Adelaide, AUSTRALIA 5005

gmirror list only showed gm0; it did did not show gm1, nor were there
any gm1* entries in /dev/mirror.

However, as soon as I have unmounted /dev/ad4s1d, /dev/ad4s1e,
and /dev/ad4s1f, gm1 was "automagically" created:

Jan  4 20:21:27 <0.2> isolde kernel: GEOM_MIRROR: Device mirror/gm1 launched (1/1).
Jan  4 20:21:27 <0.2> isolde kernel: GEOM: mirror/gm1s1: geometry does not match label (16h,63s != 255h,63s).
Jan  4 21:22:32 <0.2> isolde kernel: GEOM_MIRROR: Device gm1: rebuilding provider ad6.

Don't quite understand why creating gm1 happened only after unmounting
the filesystems on ad4.

-- 
Janos Dohanics