How to remove vestigial gmirror device?

[Doug White]

On Sat, 19 Feb 2005, Remo Lacho wrote:

> Installed 5.3-Stable from the February ISO Snapshot on an old Pentium Pro
> 600MH ATX box with 256MB memory and two WD UDMA33 6.4GB drives.
>
> After several false starts with GMirror (guided by Ralf S. Engelschal's
> excellent How-To <http://people.freebsd.org/~rse/mirror/>) the system is
> now stable and has survived many kernel recompiles without incident.
>
> One problem, one of the original test GMirror devices refused to go away.
> It did not respond to the "remove" or "forget" parameters.
>
> The "deactivate" parameter seemed to do the trick, however, upon boot-up
> the following message is generated:
>
> "GEOM_MIRROR: Device gmusr: provider ad4 marked as inactive, skipping."
>
> The "list" parameter does not list the gmusr device as being active.
>
> When "gmirror activate gmusr ad4" is invoked the response is:
>
> "Cannot write metadata from ad4: Operation not permitted.
> Not fully done."

If ad4 is your root device, GEOM prohibits changes to the device
configuration on a mounted device.  You can either:

a) boot into the fixit CD, finagle some symlinks to make 'gmirror' work (I
think you need to symlink /dist/usr/lib to /usr/lib) and remove it from
there; or
b) set 'sysctl kern.geom.debugflags=16' which disables the protection. You
activate this at your own risk, since it makes it possible to destroy the
root volume while it is mounted.

-- 
Doug White                    |  FreeBSD: The Power to Serve
dwhite at gumbysoft.com          |  www.FreeBSD.org