Take the 2-minute tour ×
Ask Ubuntu is a question and answer site for Ubuntu users and developers. It's 100% free, no registration required.

here my problem:

I am running ubuntu 12.04 on a raid10 (4 disks), on top of which I installed an lvm with two volume groups (one for /, one for /home).

The layout of the disks are as follows:

Disk /dev/sda: 1500.3 GB, 1500301910016 bytes
255 heads, 63 sectors/track, 182401 cylinders, total 2930277168 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: 0x0003f3b6


   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *          63      481949      240943+  83  Linux
/dev/sda2          481950  2910640634  1455079342+  fd  Linux raid autodetect
/dev/sda3      2910640635  2930272064     9815715   82  Linux swap / Solaris

Disk /dev/sdb: 1500.3 GB, 1500301910016 bytes
255 heads, 63 sectors/track, 182401 cylinders, total 2930277168 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: 0x00069785


   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1              63  2910158684  1455079311   fd  Linux raid autodetect
/dev/sdb2      2910158685  2930272064    10056690   82  Linux swap / Solaris

Disk /dev/sdc: 1500.3 GB, 1500301910016 bytes
255 heads, 63 sectors/track, 182401 cylinders, total 2930277168 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  2910158684  1455079311   fd  Linux raid autodetect
/dev/sdc2      2910158685  2930272064    10056690   82  Linux swap / Solaris

Disk /dev/sdd: 1500.3 GB, 1500301910016 bytes
255 heads, 63 sectors/track, 182401 cylinders, total 2930277168 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: 0x000f14de


   Device Boot      Start         End      Blocks   Id  System
/dev/sdd1              63  2910158684  1455079311   fd  Linux raid autodetect
/dev/sdd2      2910158685  2930272064    10056690   82  Linux swap / Solaris

The first disk (/dev/sda) contains the /boot partition on /dev/sda1. I use grub2 to boot the system off this partition.

On top of this raid10 I installed two volume groups, one for /, one for /home.

This system worked well, I even exchanged two disks during the last two years. It always worked. But not this time.

For the first time, /dev/sda broke. I do not know if this is an issue – I know I would have struggled anyways to overcome the problem with /boot installed on that disk and grub2 installed on the mbr of /dev/sda.

Anyways, I did what I always did:

  • start knoppix
  • fire up the raid

    sudo mdadm --examine -scan
    

    which returns

    ARRAY /dev/md127 UUID=0dbf4558:1a943464:132783e8:19cdff95
    

    start it up

    sudo mdadm --assemble /dev/md127
    
  • fail the failing disk (smart event)

    sudo mdadm /dev/md127 --fail /dev/sda2
    
  • remove the failing disk

    sudo mdadm /dev/md127 --remove /dev/sda2
    
  • stop the raid

    sudo mdadm -S /dev/md127
    
  • take out the disk
  • replace it with a new one
  • create the same partitions as on the failling one
  • add it to the raid

    sudo mdadm --assemble /dev/md127
    sudo mdadm /dev/md127 --add /dev/sda2
    
  • wait 4 hours

All looks fine:

cat /proc/mdstat

returns:

Personalities : [raid10] 
md127 : active raid10 sda2[0] sdd1[3] sdc1[2] sdb1[1]
      2910158464 blocks 64K chunks 2 near-copies [4/4] [UUUU]

unused devices: <none>

and

sudo mdadm --detail /dev/md127

returns

/dev/md127:
        Version : 0.90
  Creation Time : Wed Jun 10 13:08:46 2009
     Raid Level : raid10
     Array Size : 2910158464 (2775.34 GiB 2980.00 GB)
  Used Dev Size : 1455079232 (1387.67 GiB 1490.00 GB)
   Raid Devices : 4
  Total Devices : 4
Preferred Minor : 127
    Persistence : Superblock is persistent

    Update Time : Thu Mar 21 16:27:40 2013
          State : clean 
 Active Devices : 4
Working Devices : 4
 Failed Devices : 0
  Spare Devices : 0

         Layout : near=2
     Chunk Size : 64K

           UUID : 0dbf4558:1a943464:132783e8:19cdff95 (local to host Microknoppix)
         Events : 0.4824680

    Number   Major   Minor   RaidDevice State
       0       8        2        0      active sync   /dev/sda2
       1       8       17        1      active sync   /dev/sdb1
       2       8       33        2      active sync   /dev/sdc1
       3       8       49        3      active sync   /dev/sdd1

However, there is no trace of the volume groups. Rebooting into knoppix does not help Restarting the old system (I actually replugged and re-added the failing disk for that – the system begins to start, but then fails to see the / partition – no wonder if the volume group is gone) does not help.

sudo vgscan, sudo vgdisplay, sudo lvs, sudo lvdisplay, sudo vgscan –mknodes all returned No volume groups found.

I am completely at a loss. Can anyone tell me if and how I can recover my data?

Thanks in advance!

share|improve this question
add comment

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Browse other questions tagged or ask your own question.