I'm running fsck and getting "ext2fs_open2: Bad magic number in super-block"

Question

I'm running:

fsck -n /dev/sdb2

and I'm getting:

fsck from util-linux 2.31.1
e2fsck 1.44.1 (24-Mar-2018)
ext2fs_open2: Bad magic number in super-block
fsck.ext2: Superblock invalid, trying backup blocks...
fsck.ext2: Bad magic number in super-block while trying to open /dev/sdb2

The superblock could not be read or does not describe a valid ext2/ext3/ext4
filesystem.  If the device is valid and it really contains an ext2/ext3/ext4
filesystem (and not swap or ufs or something else), then the superblock
is corrupt, and you might try running e2fsck with an alternate superblock:
    e2fsck -b 8193 <device>
 or
    e2fsck -b 32768 <device>

Any advice? What's wrong with the partition and what should I do about it??

Additional information, as requested:

sudo fdisk -l

outputs:

Device        Start      End  Sectors  Size Type
/dev/sdb1  32335872 60061695 27725824 13.2G Microsoft basic data
/dev/sdb2      2048     4095     2048    1M BIOS boot
/dev/sdb3      4096   503807   499712  244M EFI System
/dev/sdb4    503808  4610047  4106240    2G Linux filesystem
/dev/sdb5   4610048 32335871 27725824 13.2G Linux filesystem

I was trying to back up USB stick using Clonezilla and I thought I have to run fsck on all partition to make sure that there is no problem. — BlueSkies, Nov 13 '19 at 23:40
Clonezilla might not be the best way to back up a USB stick. Why are you trying to do that? dd might be a better tool. Type man dd for more info. BE CAREFUL... if you give an incorrect dd command you could wipe out the wrong disk. — heynnema, Nov 13 '19 at 23:43
@heynnema: I was advised to use Clonezilla for backup, that's why I'm using Clonezilla. — BlueSkies, Nov 13 '19 at 23:45
Clonezilla won't clone anything to a smaller destination (even smaller by only 1 block). Why are you trying to back up a USB stick? — heynnema, Nov 13 '19 at 23:48
@heynnema: I'm trying to back up a USB stick, because it has all the system files and data on it. I'm running Ubuntu live with persistent storage from that USB stick. — BlueSkies, Nov 13 '19 at 23:52
Generally not a good idea to try and run a live system from a USB stick. Performance and space issues are a problem. — heynnema, Nov 13 '19 at 23:53

heynnema · Accepted Answer · 2019-11-13T23:41:27.017

You're doing the fsck on the wrong partition (sdb2).

sudo fdisk -l shows us that the following partitions are "Linux filesystem"...

/dev/sdb4    503808  4610047  4106240    2G Linux filesystem
/dev/sdb5   4610048 32335871 27725824 13.2G Linux filesystem

Here are the commands that you should be using...

Boot to Ubuntu Live DVD/USB in "Try Ubuntu" mode.

Open the terminal application and type:

sudo fsck -f /dev/sdb4
sudo fsck -f /dev/sdb5
reboot

I'm running fsck and getting "ext2fs_open2: Bad magic number in super-block"

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