On Tue, Aug 29, 2006 at 03:38:25PM +0200, Uwe Lienig wrote:
> After the raid was initially created two years ago, auto config was 
> switched on.
> 
> raidctl -A yes /dev/raid0
[...]
> Step 2
> ------------------------------------
> 
> To get the raid going again, I decided to copy sd31 to sd33 (the cold
> spare).  This would allow the raid to come up since there will be no
> hard errors. To copy I used (all disks are identical)
> 
> dd if=/dev/rsd31c bs=1b conv=noerror,sync of=/dev/rsd33c
> 
> I know, that there will be some blocks with wrong infos in them (dd
> will produce blocks filled with null bytes on read errors). sd30
> remains as failed. But sd31 will not produce read errors anymore. Thus
> the building of the raid will succeed.
> 
> Then I edited /etc/raid0.conf and changed sd31 to sd33 looking as
> 
> START disks
> /dev/sd10b
> /dev/sd11b
> /dev/sd12b
> /dev/sd30b
> # changed sd31 to sd33
> /dev/sd33b
> /dev/sd32b
> 
> I didn't change the spare line.
> 
> After a reboot the raid came up correctly and was configured
> automagically.  Since all the filesystems that where on the raid were
> commented out the raid remained untouched after configuration.
> 
> raidctl -s /dev/raid0
> 
> showed
> 
>            /dev/sd10b: optimal
>            /dev/sd11b: optimal
>            /dev/sd12b: optimal
>            /dev/sd30b: failed
>            /dev/sd31b: optimal
>            /dev/sd32b: optimal
>            spares: no spares
> and
>            Parity status: dirty
>            Reconstruction is 100% complete.
>            Parity Re-write is 100% complete.
>            Copyback is 100% complete.
> 
> 
> Two questions: why is sd31 not replaced by sd33?

because the system is set to autoconfigure the RAID.  since it had been
configured during boot-up, it will not be reconfigured from raid0.conf.

I think the rest of your confusion can be traced to this.

good luck on recovery.

-- 
  Aaron J. Grier | "Not your ordinary poofy goof." | agrier@poofygoof.com
              "silly brewer, saaz are for pils!"  --  virt