On 03/13/2011 07:46 PM, Tom H wrote:
> On Sun, Mar 13, 2011 at 1:33 PM, Urs Beyerle<[log in to unmask]>  wrote:
>>>
>>> As part of upgrade planning for my main workstation at home (an
>>> updated SL 5.2 system), I booted from the live CD just to see if all
>>> the major devices worked. Everything worked :). Unfortunately, that
>>> act rendered my existing system unbootable.
>>>
>>> When I booted from the live CD it found and started my md RAID1
>>> partitions, including my system root partition. Nice, I had all my
>>> data there to play with. I noticed that where I had previously used
>>> /dev/md0, /dev/md1, etc..., the live CD system had created them as
>>> /dev/md122, /dev/md123, and so on, and not in the original order. I
>>> didn't think much of this, figuring my regular system would start them
>>> back in the original configuration, but apparently some metadata
>>> somewhere got changed by the live CD system and now the original
>>> system would not get past switching to the root file system with a 'no
>>> such device' error. I could see, just before going off the screen,
>>> where it had started my root partition as /dev/md125 rather than
>>> /dev/md0.
>>>
>>> I tried a couple of things to recover from this: I tried stopping and
>>> reassembling the RAID sets with the desired device names from the live
>>> CD system, and repackaging my initrd with device files for the
>>> /dev/md12* devices, but no luck. At that point I decided that, since I
>>> had already done my backups and was planning on eventually going to
>>> SL6, that I'd just push forward with a fresh install of SL6. It took a
>>> few hours that I hadn't planned on to get everything back up to speed,
>>> and I have one issue yet to work and a couple of minor things to
>>> configure.
>>>
>>> I have another retired box with the same RAID setup and it too, got
>>> hosed by the live CD. I'm going to play with this box to see if I can
>>> find a way to recover from this.
>>>
>>> Beware.
>>
>> Thanks for letting us know!
>>
>> I would be very interesting in a recovery procedure.
>>
>> I guess that it should be possible to re-assemble the raid device. So in
>> case /dev/md0 was renamed to /dev/125 and was setup with /dev/sda1
>> /dev/sdb1, you may get /dev/md0 back, if you do
>>
>> mdadm --stop /dev/125
>> mdadm --assemble /dev/md0 /dev/sda1 /dev/sdb1
>>
>> Are your raid partition of the type 0xfd (Linux RAID autodetect) or 0x83
>> (Linux)?
>>
>> If this is a general problem with the LiveCD and software raids, I would
>> like to fix it on the LiveCD.
>
> Usually md devices are renamed/renumbered when "/etc/mdadm.conf" has
> "HOMEHOST<system>" set and the metadata in the superblock has a
> different homehost value.

The file /etc/mdadm.conf does not exist on the LiveCD. Therefore the md devices should not be renamed...?
Bluejay, do you see /etc/mdadm.conf, if you boot your system with the LiveCD?