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I'm having some problems with my disks; long story.. but right now I'm trying to mount a device that was part of a 2-disk raid1. For that, I tried to assemble it into a new array, but...

% mdadm -Av /dev/md2 /dev/sdc1
mdadm: looking for devices for /dev/md2
mdadm: /dev/sdc1 is identified as a member of /dev/md2, slot 2.
mdadm: No suitable drives found for /dev/md2

I was able to do a similar thing earlier, but right now it's not working with this device, and I can't figure out why.

More information:

% mdadm -E /dev/sdc1
/dev/sdc1:
          Magic : a92b4efc
        Version : 0.90.00
           UUID : 0bf001f2:31c5e4d1:c44c77eb:7ee19756 (local to host sysresccd)
  Creation Time : Thu Mar 12 16:43:17 2009
     Raid Level : raid1
  Used Dev Size : 51199040 (48.83 GiB 52.43 GB)
     Array Size : 51199040 (48.83 GiB 52.43 GB)
   Raid Devices : 2
  Total Devices : 2
Preferred Minor : 124

    Update Time : Sat Feb 23 17:44:08 2013
          State : clean
 Active Devices : 1
Working Devices : 2
 Failed Devices : 1
  Spare Devices : 1
       Checksum : c9e77cf6 - correct
         Events : 16015185


      Number   Major   Minor   RaidDevice State
this     2       8       33        2      spare   /dev/sdc1

   0     0       8       49        0      active sync   /dev/sdd1
   1     1       0        0        1      faulty removed
   2     2       8       33        2      spare   /dev/sdc1

% fdisk -l /dev/sdc

Disk /dev/sdc: 1000.2 GB, 1000204886016 bytes
255 heads, 63 sectors/track, 121601 cylinders, total 1953525168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

   Device Boot      Start         End      Blocks   Id  System
/dev/sdc1   *          63   102398309    51199123+  fd  Linux raid autodetect
/dev/sdc2       102398310   110398679     4000185   82  Linux swap / Solaris
/dev/sdc3       110398680   976768064   433184692+  fd  Linux raid autodetect

Hmm.. now I see sdc1 appears as a spare, weird.

sdd1 is the other half of the array. I was able to mount them separately earlier, and they both passed fsck and the file data was readable. When trying to put them together again, resync failed due to a bad block on sdd (in free space, I assume). I'm not sure if sdc1 has any bad blocks.

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What RAID controller do you have? Also what distribution of Linux? I've found that "dmraid" works very well with my RAID1 rather than "madam". –  Adambean Feb 23 '13 at 16:34
    
RAID controller? This is software RAID, so the controller is mdadm. dmraid is a totally different thing. The distro is Gentoo, but I don't see how that's relevant. –  aditsu Feb 23 '13 at 16:36
    
Well, actually I guess the kernel md / raid drivers are more suited for the title of controller. –  aditsu Feb 23 '13 at 16:38
    
I use software RAID too, Intel Rapid Storage. I mount it using dmraid. (well, Ubuntu does it automatically, but madam certainly isn't being used) So there is no fakeraid device, usually from your motherboard, being used in your case? –  Adambean Feb 23 '13 at 16:45
1  
This might be a superblock not found problem (From the mdadm source code: if (super == NULL) { fprintf(stderr, Name ": No suitable drives found for %s\n", mddev);) –  Hennes Feb 23 '13 at 16:46

1 Answer 1

Try with missing in place of missing drives to activate degraded array.

mdadm -Av /dev/md2 /dev/sdc1 missing

I don't think you can easily create same array twice in the system where both are degraded.

cat /proc/mdstat 

Will list your currently active raid devices.

If the raid with sdd1 is ok then dry:

mdadm --manage /dev/md2 --add /dev/sdc1
# or
mdadm --manage /dev/md2 --re-add /dev/sdc1

(when /dev/md2 is the raid device with sdd1)

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