File Recovery from thumb drive - Bad Superblock

Question

So I have a 64GB SanDisk Cruzer Glide, and recently something happened to it. Whenever I would try to fsck it said the magic number for the superblock was corrupted, I didn't know what that meant, so I backed up everything with dd to a 1TB hard drive.

I formatted it as exFAT in macOS, and put it back into my Pi 400. I tried to mount the .img file to a directory I made so I can try to copy the files over to the thumb drive, so I can then copy them to my hard drive, but whenever I try to mount the .img file, I get this...

root@ubuntu:/home/wolfyn_claw# mkdir /mnt/glide2
root@ubuntu:/home/wolfyn_claw# mount -o loop '/media/wolfyn_claw/AC_STORAGE/glide2.img' /mnt/glide2
mount: /mnt/glide2: wrong fs type, bad option, bad superblock on /dev/loop17, missing codepage or helper program, or other error.

I'm attempting to write the .img file back to the thumb drive and see how that goes. I'm really hoping I can access the files on it, I can't afford to lose any of it.

I attempted to fsck the thumb drive, but whenever I do so it says the magic number in he superblock is invalid.

Before I did this, I backed up the thumb drive dev/sda1 to an .IMG file with dd. The file is ~63.5GB, and is stored on my hard drive.

Help is really appreciated, I really need to get these files back. Once it works again, I'll transfer everything to my 2TB SSD.

Answer 1

so I backed up everything with dd to a 1TB hard drive.

That is the best action that you did. When you try anything, do it on a copy of this file, not on this file itself.

First make a copy of the image and work on that copy. If anything goes wrong, you will still have the original image.

The fact that you use fsck on the original image suggests that you have, at one point, formatted it as ext2/3/4. The original superblock is gone, but there may be valid backups. Use

dumpe2fs /dev/sda5 | grep -i superblock

to find them.

You will get lines that say

Backup superblock at 98304, Group descriptors at 98305-98537

So, try to mount it with:

mount -o sb=98304 -o loop '/media/wolfyn_claw/AC_STORAGE/glide2.img' /mnt/glide2

If that superblock does not work, try another one.

----- edit -----

You should have dd-ed the whole disk, probably with

dd if=/dev/sda of=/some/image.img

In that case, you will need to mount the correct partition in the image. You will need to mount it with an offset.

To determine the offset, do

fdisk -l imagefile

Calculate the offset = start sector * size of a sector in bytes and mount with

mount -o ro,loop,offset=<offset you calculated> -t auto imagefile /mnt/mountpoint