gmirror gm0 destroyed on shutdown; GPT corrupt

[Pawel Jakub Dawidek]

On Tue, Jun 30, 2009 at 02:37:55PM -0700, Marcel Moolenaar wrote:
> 
> On Jun 29, 2009, at 2:00 PM, Rick C. Petty wrote:
> 
> >[[ Removing the double cross-post, since this is GEOM-specific ]]
> >
> >On Sat, Jun 27, 2009 at 06:20:49PM -0700, Marcel Moolenaar wrote:
> >>
> >>Using the last sector is not only flawed because it creates a race
> >>condition,
> >
> >It shouldn't create a race condition.
> 
> It does.
> 
> Answer the following:
> 
> foo0 is a provider with 3 sectors.
> bar is a geom class that puts meta-data in the first sector.
> baz is a geom class that puts meta-data in the last sector.
> 
> Both bar and baz get to taste foo0. Which one should go first?

Marcel, I don't think you expect than entire world will agree on one
place where metadata should be stored? A provider can contain metadata
of few independent GEOM classes and its class responsibility to detect
its providers correctly.

Even for my classes where I store provider size in metadata there are
configurations I can't cope with cleanly, like the 'c' partition.
Workaround I implemented is to store provider name in metadata, but of
course it's problematic if your disk name will change.

All in all there is nothing wrong with gmirror.

In your example you want all metadata formats to be exact same size
and stored in exact same place...

-- 
Pawel Jakub Dawidek                       http://www.wheel.pl
pjd at FreeBSD.org                           http://www.FreeBSD.org
FreeBSD committer                         Am I Evil? Yes, I Am!
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