[ale] Reassembling a software raid array

John Wells jb at sourceillustrated.com
Sun Jul 29 09:17:57 EDT 2007


Guys,

I have a desktop at home that's been running Ubuntu LTS (Dapper) for some time. I finally got around to upgrading last night. However, I've run into a bit of a complication with my software raid config.

Turns out this box is also my backup dumping group. I had to RAID1 arrays configured:

/dev/hda2 and /dev/sda2 formed a 150GB array, on which I had LVM configured. This was the main "drive" where the OS and /home and /opt partitions lived

/dev/sdc1 and /dev/sdb1 formed a 250 GB array, upon which I had on LVM volume that was mounted on /BACKUP. This is where my "backups" for a few boxes live (yes, I'm aware that raid isn't backup).

When installing Fiesty, I kept running into problems when configuring software raid. On a hunch, I unplugged the drives sdb and sdc, and voila, everything worked. Installed went flawlessly, I was able to replicate the first RAID above and install Fiesty.

So, I'm booted up now, and /dev/md0 is formed for the first array. However, I need to reinitialize my /dev/md1 device with /dev/sdb1 and /dev/sdc1, WITHOUT overwriting or losing data. I would be heartbroken to lose a few files there.

Anyone know how to do this? It would appear that mdadm --assemble should work, but when I try it:

root at box# mdadm --assemble /dev/md1 /dev/sdb1 /deb/sdc1
mdadm: /dev/md1 is not a block device.

root at box# file /dev/md{0,1}
/dev/md0: block special (9/0)
/dev/md1: symbolic link to `md/1'

root at box# mdadm -D /dev/md0
/dev/md0:
        Version : 00.90.03
  Creation Time : Sat Jul 28 23:18:58 2007
     Raid Level : raid1
     Array Size : 116238208 (110.85 GiB 119.03 GB)
    Device Size : 116238208 (110.85 GiB 119.03 GB)
   Raid Devices : 2
  Total Devices : 2
Preferred Minor : 0
    Persistence : Superblock is persistent

    Update Time : Sun Jul 29 09:04:21 2007
          State : clean
 Active Devices : 2
Working Devices : 2
 Failed Devices : 0
  Spare Devices : 0

           UUID : cdd1704f:4e0549a6:3c221302:a751f5d2
         Events : 0.8

    Number   Major   Minor   RaidDevice State
       0       3        2        0      active sync   /dev/hda2
       1       8        2        1      active sync   /dev/sda2

root at box# mdadm -D /dev/md1 
mdadm: md device /dev/md1 does not appear to be active.

Any help (outside of telling me to buy a tape drive ;) ) you can offer will be GREATLY appreciated!

Thanks,
John



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