Single RAID1 disk - mounting via USB

[divine-wind]

Hi

I have a single 4TB drive rescued from a dead Debian9 server

The drive contains data only and was part of a RAID1 array and now sits in a USB caddy attached to a headless Ubuntu 22.04 server

#fdisk -l
Disk /dev/sdc: 3.64 TiB, 4000787030016 bytes, 7814037168 sectorsDisk model: EFRX-68N32N0    
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: gpt
Disk identifier: 5DAF00AF-DD46-4C9C-A259-D72F635A8D10


Device     Start        End    Sectors  Size Type
/dev/sdc1 2048 7814035455 78140334083.6T Linux RAID

but ..

#sudo mount -t ext4 /dev/sdc1 /mnt/xtunes
mount: /mnt/xtunes: /dev/sdc1 already mounted or mount point busy

and ..

#sudo mdadm --examine /dev/sdc1:
          Magic : a92b4efc
        Version : 1.2
    Feature Map : 0x1
     Array UUID : c73ad58e:2a40147a:09e81df6:2566dd07
           Name : roonserver:0
  Creation Time : Sun Jun 10 19:02:55 2018
     Raid Level : raid1
   Raid Devices : 2


 Avail Dev Size : 7813771264 sectors (3.64 TiB 4.00 TB)
     Array Size : 3906885632 KiB (3.64 TiB 4.00 TB)
    Data Offset : 262144 sectors
   Super Offset : 8 sectors
   Unused Space : before=262056 sectors, after=0 sectors
          State : clean
    Device UUID : cb590e0b:1222edb0:cc227568:ca3e84cf


Internal Bitmap : 8 sectors from superblock
    Update Time : Sun Jan 28 14:29:28 2024
  Bad Block Log : 512 entries available at offset 72 sectors
       Checksum : 1d3bc8b9 - correct
         Events : 217230




   Device Role : Active device 0
Array State : AA ('A' == active, '.' == missing, 'R' == replacing)

Is it possible to mount this partition so I can rescue the data please?


Many thanks for any help

[TheFu]

You need to assemble a partial array. That will create a RAID device with a file system that can be mounted. I'd have to look up the mdadm commands in the mdadm manpage, so I figure you can do that yourself just as easily.

I'm assuming this was a software-RAID array and created using mdadm. If that isn't the situation, ignore what I've posted. IDK. If Fake-RAID was used, you will probably need an identical motherboard with identical disk controller, to gain any access.

[MAFoElffen]

You should be able to do

mdadm --assemble /dev/md1 --run /dev/sdc1

Adjust to whatever the md device name. The "--run" option there tells it not to abort if there is a missing device (the other half of the RAID1)... So that way it can come up as half of the RAID1.

Then you can backup what you need to get off there, or recreate the other half of that to another drive... By adding in a new drive via

sudo mdadm --manage /dev/md1 --add /dev/sdd1

Or whatever your plan is from here....

TheFu talked me out of working more on the mdmadm-gui Project I was working on... Enough said on that. LOL.