I'm working with a Synology RAID1 system and deleted a file that wasn't yet backed up. To recover the file, and since an undelete approach seems to be impossible, my idea is to mount a single RAID1 disk in Ubuntu 20.04 LTS and search for it, but I'm having some trouble with it. An internet search brought me to two related Q&A's here; they are of older date though and didn't work in my case.
From lsblk:
sdb 8:16 0 5.5T 0 disk
├─sdb1 8:17 0 2.4G 0 part
├─sdb2 8:18 0 2G 0 part
├─sdb5 8:21 0 2.7T 0 part
└─sdb6 8:22 0 2.7T 0 part
Attempt 1, usual mount attempt:
Usual mount doesn't recognize the file system.
# mount /dev/sdb1 /mnt/test/
mount: /mnt/test: unknown filesystem type 'linux_raid_member'.
Attempt 2 using mdadm (Ref)
When trying to apply the first solution, the superblock seems to be missing.
# mdadm --assemble --run /dev/md0 /dev/sdb1
mdadm: no recogniseable superblock on /dev/sdb1
mdadm: /dev/sdb1 has no superblock - assembly aborted
Attempt 3 using losetup (Ref)
However the issue persists even with the second solution.
# losetup /dev/loop18 /dev/sdb1 -o 1048576
# mount /dev/loop18 /mnt/test/
mount: /mnt/test: wrong fs type, bad option, bad superblock on
/dev/loop18, missing codepage or helper program, or other error.
Altogether this shows me I probably could need some help. Can anyone provide me with a working solution? Please note that the main goal is to recover the file, not necessarily in a specific way.
Edit
More outputs:
# file -s /dev/sdb?
/dev/sdb1: Linux rev 1.0 ext4 filesystem data, UUID=ceb6a1e0-2bde-441f-97dc-db231fc51d41, volume name "1.41.12-1963" (extents) (large files) (huge files)
/dev/sdb2: Linux/i386 swap file (new style), version 1 (4K pages), size 524271 pages, no label, UUID=abbd2e2f-a7a4-4e5d-bd79-55908f8ff79d
/dev/sdb5: Linux Software RAID version 1.2 (1) UUID=a7c85951:8b8b7689:d4ad5498:e14c55d1 name=DiskStation:2 level=1 disks=2
/dev/sdb6: Linux Software RAID version 1.2 (1) UUID=69b042ac:84e2b185:501c0c3e: c12533 name=WOTAN:3 level=1 disks=2
