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CaeriTech

Member

Registered: 2021-07-12

Posts: 31

[SOLVED] mdadm 4.3-2 no superblock

Synopsis: Re-created the backup arrays using partitions.  Luckily I use detached header and key files for the data array and they were unaffected.  I can fully access the data array.

I use several HDDs and SSDs that I use for various RAID arrays and today when attempting to assemble them I get the following message for all drives:

mdadm: looking for devices for /dev/mdX
mdadm: Cannot assemble mbr metadata on /dev/sdX
mdadm: /dev/sdX has no superblock - assembly aborted

I can't imagine that I did something to fry all of the drives at the same time.  Am I missing something here?

Last edited by CaeriTech (2024-04-12 14:55:25)

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-=[ LIVE enabled UEFI with redundant syslinux pure systemd detached LUKS header partitionless encrypted GPT SSDx3 RAID0 wayland only because I can.  ]=-
    Backward compatibility is for the masses. There's no dual-boot here.

    [CaeriTech remains only artificially intelligent.  Turing would be aghast at just how artificial.]

frostschutz

Member

Registered: 2013-11-15

Posts: 1,476

Re: [SOLVED] mdadm 4.3-2 no superblock

Did you use partitions, or whole drives, in your raid array? In case of whole drives, it may be something created partition tables and killed metadata in the process. It's safer to use partitions... more software knows to leave those alone, vs. an unpartitioned drive looks fair game.

If nothing else happened, it may still be recoverable, if you're able to determine drive order, data offset, raid layout, etc.

mdadm 4.3 also has issues with mdX for X>128 but the error message would look different ("not posix compatible"), so that's probably not it.

mdadm --examine? mdadm.conf? (if it lists device names in ARRAY lines, try just the UUIDs)

Last edited by frostschutz (2024-04-03 20:22:01)

CaeriTech

Member

Registered: 2021-07-12

Posts: 31

Re: [SOLVED] mdadm 4.3-2 no superblock

Yes I used whole drives without any partitions.  One of the arrays was RAID1 mirrored.  Would that make it any easier to determine the data offset, raid layout, etc. to recover the mbr metadata?  Are there any tools to do this?

I should also mention that the array is encrypted with cryptsetup 2.7.1-1.

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-=[ LIVE enabled UEFI with redundant syslinux pure systemd detached LUKS header partitionless encrypted GPT SSDx3 RAID0 wayland only because I can.  ]=-
    Backward compatibility is for the masses. There's no dual-boot here.

    [CaeriTech remains only artificially intelligent.  Turing would be aghast at just how artificial.]

frostschutz

Member

Registered: 2013-11-15

Posts: 1,476

Re: [SOLVED] mdadm 4.3-2 no superblock

If it's LUKS2, you can find the offset by following the metadata recovery / partition recovery steps in this answer https://unix.stackexchange.com/a/741850/30851

If you want to attempt recovery using mdadm --create, do use copy-on-write overlays ... also see https://unix.stackexchange.com/a/131927/30851

CaeriTech

Member

Registered: 2021-07-12

Posts: 31

Re: [SOLVED] mdadm 4.3-2 no superblock

Thank frostschutz.  Both of those links were very informative.

Luckily I use detached header and key files for my data array so they were unaffected and I was able to fully access the array.  I decided to re-create the backup arrays using partitions as you suggested using partitions was safer.  I'll mark this as solved.

---

-=[ LIVE enabled UEFI with redundant syslinux pure systemd detached LUKS header partitionless encrypted GPT SSDx3 RAID0 wayland only because I can.  ]=-
    Backward compatibility is for the masses. There's no dual-boot here.

    [CaeriTech remains only artificially intelligent.  Turing would be aghast at just how artificial.]