geom stripe/concat metadata suggestion

[Pawel Jakub Dawidek]

On Fri, Aug 06, 2004 at 09:38:21PM +1000, Sam Lawrance wrote:
+> 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.

Yes, this is a problem, but I'm not going to store provider's name in the
metadata, because now, you just copy disk with 'dd' and your stripe still
works.

As a workaround you shouldn't use last sector on ad0s1d. If you don't want
to change partition, you can use gnop(8) for this:

	# gstripe clear ad0s1d
	# gnop create -s `diskinfo ad0s1d | awk '{print $3 - 512}'` ad0s1d
	# gstripe label <name> <first_component> ad0s1d.nop

But in such case it will not be automatically discovered at boot time.

The best solution probably is to not use last disk sector...

Hmm, when such conflict is detected I should probably destroy whole device,
instead of configuring it from first component found.

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