Bad magic number in super-block

**peyre** · October 26th, 2024

I'm running Xubuntu 24.04 on a 512GB SSD (ext4) and am not experiencing issues, except I checked dmesg the other day and it returned errors like these:

Code:

[ 2545.428343] sd 7:0:0:0: [sdd] tag#0 FAILED Result: hostbyte=DID_OK driverbyte=DRIVER_OK cmd_age=0s
[ 2545.428366] sd 7:0:0:0: [sdd] tag#0 Sense Key : Medium Error [current] 
[ 2545.428376] sd 7:0:0:0: [sdd] tag#0 Add. Sense: Unrecovered read error
[ 2545.428387] sd 7:0:0:0: [sdd] tag#0 CDB: Read(10) 28 00 00 00 00 04 00 00 01 00 00 00
[ 2545.428393] critical medium error, dev sdd, sector 4 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 0
[ 2545.428453] FAT-fs (sdd): FAT read failed (blocknr 4)
[ 2546.228250] sd 7:0:0:0: [sdd] tag#0 FAILED Result: hostbyte=DID_OK driverbyte=DRIVER_OK cmd_age=0s
[ 2546.228274] sd 7:0:0:0: [sdd] tag#0 Sense Key : Medium Error [current] 
[ 2546.228284] sd 7:0:0:0: [sdd] tag#0 Add. Sense: Unrecovered read error
[ 2546.228294] sd 7:0:0:0: [sdd] tag#0 CDB: Read(10) 28 00 00 00 00 04 00 00 04 00 00 00
[ 2546.228301] critical medium error, dev sdd, sector 4 op 0x0:(READ) flags 0x80700 phys_seg 4 prio class 0
[ 2547.028177] sd 7:0:0:0: [sdd] tag#0 FAILED Result: hostbyte=DID_OK driverbyte=DRIVER_OK cmd_age=0s
[ 2547.028201] sd 7:0:0:0: [sdd] tag#0 Sense Key : Medium Error [current] 
[ 2547.028211] sd 7:0:0:0: [sdd] tag#0 Add. Sense: Unrecovered read error
[ 2547.028259] sd 7:0:0:0: [sdd] tag#0 CDB: Read(10) 28 00 00 00 00 04 00 00 01 00 00 00
[ 2547.028268] critical medium error, dev sdd, sector 4 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 0
[ 2547.028332] FAT-fs (sdd): FAT read failed (blocknr 4)

So this morning I fired the system up with a live disk, and ran sudo fsck -y /dev/sda, and it returned this sort of thing:

Code:

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/sda

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>
of
  e2fsck -b 32768 <device>

Found a gpt partition table in /dev/sda

Running e2fsck -b 8193 /dev/sda or the same for 32768 returns:

Code:

e2fsck: Bad magic number in super-block while trying to open /dev/sda

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>
of
  e2fsck -b 32768 <device>

Found a gpt partition table in /dev/sda

**tea for one** · October 26th, 2024

Originally Posted by peyre

So this morning I fired the system up with a live disk, and ran sudo fsck -y /dev/sda, and it returned this sort of thing:

You should run fsck on a partition not the disk

Code:

sudo fsck /dev/sda1

Code:

sudo fsck /dev/sda2

**peyre** · October 26th, 2024

Ha! That simple, eh? I'll reboot and try it.

**peyre** · October 26th, 2024

That definitely changed things. I have the default partitioning for Xubuntu, so my system is on sda3. Running sudo fsck -y /dev/sda3 returns:

Code:

fsck from util-linux 2.39.3
e2fsck 1.47.0 (5-Feb-2023)
/dev/sda3: clean, 637041/31227904 files, 57322824/124894976 blocks

Now it returned this immediately, so I image it wasn't really checking the file system thoroughly. Is/are there different switches I should be using?

**Rubi1200** · October 27th, 2024

You could try this:

Code:

sudo e2fsck -C0 -p -f -v /dev/sda3

Make sure partitions are unmounted and change sda3 to whatever if needed.

The command will force a full check and fix minor errors as well as displaying the progress and output in the terminal.

**peyre** · October 27th, 2024

Thanks! Here's the result. Looks like I'm probably ok?

Code:

/dev/sda3:                                                                      Inode 17302118 extent tree (at level 1) could be shorter.  IGNORED.
/dev/sda3: Inode 17317590 extent tree (at level 2) could be narrower.  IGNORED.
/dev/sda3: Inode 17318374 extent tree (at level 2) could be narrower.  IGNORED.
/dev/sda3: Inode 17319905 extent tree (at level 1) could be narrower.  IGNORED.
/dev/sda3: Inode 17320072 extent tree (at level 2) could be narrower.  IGNORED.
/dev/sda3: Inode 17320078 extent tree (at level 1) could be narrower.  IGNORED.
/dev/sda3: Inode 17323842 extent tree (at level 2) could be narrower.  IGNORED.
/dev/sda3: Inode 17325453 extent tree (at level 2) could be narrower.  IGNORED.
/dev/sda3: Inode 17325519 extent tree (at level 2) could be narrower.  IGNORED.
/dev/sda3:                                                                      Inode 18612232 extent tree (at level 2) could be narrower.  IGNORED.
/dev/sda3: Inode 18615704 extent tree (at level 1) could be narrower.  IGNORED.
/dev/sda3: Inode 18618960 extent tree (at level 2) could be narrower.  IGNORED.
/dev/sda3: Inode 18619002 extent tree (at level 1) could be narrower.  IGNORED.
/dev/sda3: Inode 18630212 extent tree (at level 2) could be narrower.  IGNORED.
/dev/sda3: Inode 18630314 extent tree (at level 2) could be narrower.  IGNORED.
/dev/sda3: Inode 18633434 extent tree (at level 1) could be narrower.  IGNORED.
/dev/sda3: Inode 18633439 extent tree (at level 2) could be narrower.  IGNORED.
/dev/sda3:                                                                      Inode 19935305 extent tree (at level 1) could be narrower.  IGNORED.
/dev/sda3: Inode 19951336 extent tree (at level 2) could be narrower.  IGNORED.
/dev/sda3: Inode 19951639 extent tree (at level 2) could be narrower.  IGNORED.
/dev/sda3:                                                                      Inode 21899432 extent tree (at level 2) could be narrower.  IGNORED.
/dev/sda3: Inode 21901218 extent tree (at level 2) could be narrower.  IGNORED.
                                                                               
      637361 inodes used (2.04%, out of 31227904)
        7180 non-contiguous files (1.1%)
         763 non-contiguous directories (0.1%)
             # of inodes with ind/dind/tind blocks: 0/0/0
             Extent depth histogram: 609158/703/15
    59366366 blocks used (47.53%, out of 124894976)
           0 bad blocks
          21 large files

      539383 regular files
       68481 directories
           8 character device files
           0 block device files
           1 fifo
          75 links
       29478 symbolic links (27467 fast symbolic links)
           1 socket
------------
      637427 files

I also accidentally ran it with a wrong switch (-c instead of -C0):

Code:

/dev/sda3: Updating bad block inode.
/dev/sda3: Inode 17302118 extent tree (at level 1) could be shorter.  IGNORED.
/dev/sda3: Inode 17317590 extent tree (at level 2) could be narrower.  IGNORED.
/dev/sda3: Inode 17318374 extent tree (at level 2) could be narrower.  IGNORED.
/dev/sda3: Inode 17319905 extent tree (at level 1) could be narrower.  IGNORED.
/dev/sda3: Inode 17320072 extent tree (at level 2) could be narrower.  IGNORED.
/dev/sda3: Inode 17320078 extent tree (at level 1) could be narrower.  IGNORED.
/dev/sda3: Inode 17323842 extent tree (at level 2) could be narrower.  IGNORED.
/dev/sda3: Inode 17325453 extent tree (at level 2) could be narrower.  IGNORED.
/dev/sda3: Inode 17325519 extent tree (at level 2) could be narrower.  IGNORED.
/dev/sda3: Inode 18612232 extent tree (at level 2) could be narrower.  IGNORED.
/dev/sda3: Inode 18615704 extent tree (at level 1) could be narrower.  IGNORED.
/dev/sda3: Inode 18618960 extent tree (at level 2) could be narrower.  IGNORED.
/dev/sda3: Inode 18619002 extent tree (at level 1) could be narrower.  IGNORED.
/dev/sda3: Inode 18630212 extent tree (at level 2) could be narrower.  IGNORED.
/dev/sda3: Inode 18630314 extent tree (at level 2) could be narrower.  IGNORED.
/dev/sda3: Inode 18633434 extent tree (at level 1) could be narrower.  IGNORED.
/dev/sda3: Inode 18633439 extent tree (at level 2) could be narrower.  IGNORED.
/dev/sda3: Inode 19935305 extent tree (at level 1) could be narrower.  IGNORED.
/dev/sda3: Inode 19951336 extent tree (at level 2) could be narrower.  IGNORED.
/dev/sda3: Inode 19951639 extent tree (at level 2) could be narrower.  IGNORED.
/dev/sda3: Inode 21899432 extent tree (at level 2) could be narrower.  IGNORED.
/dev/sda3: Inode 21901218 extent tree (at level 2) could be narrower.  IGNORED.

      637362 inodes used (2.04%, out of 31227904)
        7179 non-contiguous files (1.1%)
         763 non-contiguous directories (0.1%)
             # of inodes with ind/dind/tind blocks: 0/0/0
             Extent depth histogram: 609156/706/15
    59366901 blocks used (47.53%, out of 124894976)
           0 bad blocks
          21 large files

      539385 regular files
       68480 directories
           8 character device files
           0 block device files
           1 fifo
          75 links
       29478 symbolic links (27467 fast symbolic links)
           1 socket
------------
      637428 files

**Rubi1200** · October 29th, 2024

If the system is booting normally then I would say everything looks fine.

There are no critical errors or immediate warnings that would require attention.