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Re: Persistent superblock on software RAID



On Wed 18 Jan 2006 19:01, Mike Bird wrote:
> On Wed, 2006-01-18 at 13:50, José Pablo Ezequiel Fernández wrote:
> > I have a software RAID that has wrong persistent superblock information,
> > when I try to boot it tries to assemble the array with hdc1 and hdd1, but
> > the array really is sda1 and sdb1.
> > I am able to mount with a live CD and assemble the RAID by hand (using
> > sda1 and sdb1).
> > How can I update the superblock to hold that new information ?
> > Thank you.
>
> You can "mdadm --stop ..." the RAID and then "mdadm --create ..."
> the RAID again with the new info.
>
> To be safe, make backups first.  However, I've done it a few
> times without lossage.

There's no info yet, I am just trying to make this beast work for the first 
time.
The superblocks are updated, starting with linux 2.4 and changing the config 
file /etc/mdadm/mdadm.conf to reflect the devices as seen from linux 2.6 (hdc 
-> sda, hdd -> sdb) updated the superblocks upon stop (when halting the 
computer).
Now, when I try to boot up linux 2.6 I still get the same error: wrong 
superblock or /dev/hdc1: no such file or directory. Of course, it in 
now /dev/sda1, what/who is looking for it on /dev/hdc instead of /dev/sda ? I 
suppose something on grub or the like.
When I boot linux 2.4, I get the first device, md0 mounted correctly 
from /dev/hdc1 and /dev/hdd1 (it is evidently not reading the superblocks for 
this) but for the rest of the partitions, it reads the superblock and fails 
to boot (of course, /dev/sd[ab] doesn't oxist on linux 2.4).
Any idea what is wrong and how to fix it ?
Thank you.

-- 
José Pablo Ezequiel Fernández

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