Rescue md/software RAID array

[Matthias Brennwald]

On 6. Jul 2010, at 9:08, Matthias Brennwald wrote:

> On 6. Jul 2010, at 3:26, Christopher Chan <christopher.chan at bradbury.edu.hk> wrote:
> 
>>> I am able to boot using a rescue CD (I used the Ubuntu alternate installer disk, because the Live CD does not have md/softraid support), but I don't really know how to proceed in order to fix things. I would greatly appreciate any hints on how to get the machine up and running again. For instance, which commands should I try after booting into the Ubuntu rescue CD?
>> 
>> 
>> mdadm --assemble --scan
> 
> Result: "No arrays found in config file"
> 
> 
> On 6. Jul 2010, at 8:26, Luis Paulo <luis.barbas at gmail.com> wrote:
> 
>> # apt-get install mdadm
>> # mdadm --auto-detect
> 
> I skipped the "apt-get install" because I am using the Ubuntu Alternate Disk which already has mdadm. Then I ran "mdadm --auto-detect", which gave no result.
> 
> Do I have to specifiy the md devices explicitly somehow? These would be /dev/sdb1, /dev/sdc1 and /dev/sdd1 (plus the spare /dev/sde1)
> 
> Just a note that might be important (but I am not sure): before entering the shell of the alternate disk I was asked about the root file system and where I wanted to execute the shell. I chose "do not use a root file system" and "execute shell in installer environment".
> 
> Thanks for your help!
> 
> Matthias


I tried a little more (inspired by http://fts.ifac.cnr.it/cgi-bin/dwww/usr/share/doc/mdadm/README.recipes.gz ):
mdadm --assemble --auto=yes --force /dev/md0 /dev/sdb1 /dev/sdc1 /dev/sdd1

Result:
mdadm: cannot open device /dev/sdb1: No such file or directoy
mdadm: /dev/sdb1 has no superblock - assembly aborted

Then I looked at /dev/sdb using "fdisk -l". The output of this is too long to copy it (I am typing everything manually here, because I have no clue how to transfer a file from the machine running the rescue disk). Here are the last two lines (the rest does not mean much to me):

Device	Boot	Start	End	Blocks	Id	System
/dev/sdb1		1	243202	1953514583+	ee	GPT


What do you guys think?

Matthias