Is there a way to replace a magic superblock?

Taihlo

11/4/23, 3:43 PM

Following instructions from the Internet (Without doing research first) I have blanked out the superblock on the incorrect RAID disk. Using this command;

sudo mdadm --zero-superblock /dev/sdd

Now when I try to assemble the array I get this error;

mdadm: No super block found on /dev/sdd (Expected magic a92b4efc, got 00000000)

Is there any way to get that superblock back? the data appears to be there still, and even degraded, I would love to get this back in some form... Sadly backups of a 14 TB array are not easy, and the last one is years old :(

edit: This is Ubuntu 22.04.1 LTS and here is the original array build

    Version : 1.2   Creation Time : Sun Feb 22 12:11:32 2015
 Raid Level : raid5
 Array Size : 13673680384 (13040.24 GiB 14001.85 GB)   Used Dev Size : 1953382912 (1862.89 GiB 2000.26 GB)    Raid Devices : 8   Total

Devices : 8 Persistence : Superblock is persistent

Update Time : Sun Feb 22 12:16:32 2015
      State : clean, degraded, recovering   Active Devices : 7 Working Devices : 8  Failed Devices : 0   Spare Devices : 1

     Layout : left-symmetric
 Chunk Size : 512K

Rebuild Status : 0% complete

       Name : guppy:0  (local to host guppy)
       UUID : 638274dd:1e546e4f:2d6c6d10:ee3ca38d
     Events : 12

Number   Major   Minor   RaidDevice State
   0       8       16        0      active sync   /dev/sdb
   1       8       32        1      active sync   /dev/sdc
   2       8       48        2      active sync   /dev/sdd
   3       8       64        3      active sync   /dev/sde
   4       8       80        4      active sync   /dev/sdf
   5       8       96        5      active sync   /dev/sdg
   6       8      112        6      active sync   /dev/sdh
   8       8      128        7      spare rebuilding   /dev/sdi

1 + 3

disk

raid

mdadm

hard-drive

disk-management

David

11/4/23, 3:56 PM

Is there a version of Ubuntu being used?

David

11/4/23, 3:57 PM

You can try the answers from this question https://unix.stackexchange.com/questions/643923/mdadm-does-not-find-the-superblock-during-the-assemble-operation

Taihlo

11/8/23, 3:44 PM

Thank you, but that didn't have any options for this situation...

Score:0

Ubuntu

Taihlo

11/11/23, 8:05 PM

Thanks for all the assistance, but I wasn't able to get the array back with the data. I ended up having to replace one of the physically bad drives, and just couldn't get anything to recover. I can see the data is still on the disk using TestDisk utility, however I can't recover any partitions, so I will need to rebuild. I learned a lot...

+ 0

Elon Musk

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EN: Is there a way to replace a magic superblock?

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