geom stripe/concat metadata suggestion

[Dan Nelson]

In the last episode (Aug 06), Sam Lawrance said:
> Would it be a good idea to store the device name, or something
> similar, in the metadata?
> 
> For example, if I have a disk divided like this:
> 
>  |--------------ad0--------------|
>  |-------------ad0s1-------------|
>  |----ad0s1g-----|-----ad0s1d----|
> 
> The metadata is written into the last sector, so when the
> stripe/concat classes are tasting they can't work out whether it
> belongs to ad0s1d, ad0s1 or ad0.
> 
> I've had problems creating stripes and concats with this configuration.

Does the metadata store the device size?  If so, then only ad0 and
ad0s1 match, and it doesn't really matter which ends up being used.

I'd be wary of embedding the device name because of shifting names if
you add or shuffle disks around.

-- 
	Dan Nelson
	dnelson at allantgroup.com