graid3 not working on partitions

[Pawel Jakub Dawidek]

On Wed, Nov 24, 2004 at 09:20:33AM +0100, Michael Reifenberger wrote:
+> Hi,
+> since GEOM so a nicely layered framework (and I didnt want to loose my MBR)
+> I tried to setup a graid3 using using da1s1a... instead of da1...
+> getting the following negative results:
+> (not only trying to use da1/da1s1 for parity,
+>  it trashes the disklabel on da1s1 too)
+> 
+> ...
+> (totum)(root) graid3 label -r -v data da3s1a da4s1a da1s1a
+> GEOM_RAID3: Device data created (id=224).
+> GEOM_RAID3: Device data: provider da3s1a detected.
+> Metadata value stored on da3s1a.
+> GEOM_RAID3: Device data: provider da4s1a detected.
+> Metadata value stored on da4s1a.
+> GEOM_RAID3: Device data: provider da1 detected.

The thing you have to avoid (probably it should be more clear in the
manual page) is to allow providers to share the same last sector.
The gradi3 class uses the last provider's sector to store metadata
and if you have 2 or more providers which share this sector you are
in troubles. In your case da1, da1s1 and da1s1a providers use the
same last sector and graid3 is confused and picks first provider
given by GEOM for taste.
You should create labels once again and leave the last sector on da1s1
unused, so da1s1 and da1s1a don't end at the same offset.

-- 
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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