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#1 2020-11-20 18:16:40

nobodyuknow
Member
Registered: 2017-09-10
Posts: 74  

SOLVED: Bad magic number in super-block

I believe the USB 3.0 ports on my 2013 laptop (HP with Intel 3rd Generation Core processor, 8 GB memory) are no longer reliable. I say that because a few times I have seen the strange visuals one only sees after accidentally unplugging the cable from the external SSD. One of them was bad, so I used the other one, thinking it was okay. If only.

Today I saw a message telling me that the thumbnail cache was corrupted (or words to that effect). Clicking on FIX did not fix the problem. I rebooted, only the system was unable to boot because of corruption (it told me to fsck). I shut it down and restarted using a Sparky Linux USB flash drive plugged into a USB 2.0 port. I unmounted the drive using GParted and tried to fsck, but received the below message:

sudo fsck /dev/sdc
fsck from util-linux 2.33.1
e2fsck 1.44.5 (15-Dec-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/sdc

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>

Found a dos partition table in /dev/sdc

I tried both of the suggested commands, but received essentially the same message.

Is it time for a rebuild?

Last edited by nobodyuknow (2020-11-20 18:57:58)

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#2 2020-11-20 18:30:05

Head_on_a_Stick
Member
From: London
Registered: 2019-03-24
Posts: 1,139  
Website

Re: SOLVED: Bad magic number in super-block

Did you try using fsck on the partition?

For example

# fsck /dev/sdc1

Replace 1 with the correct partition number.


Black Lives Matter

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#3 2020-11-20 18:51:07

nobodyuknow
Member
Registered: 2017-09-10
Posts: 74  

Re: SOLVED: Bad magic number in super-block

@Head_on_a_Stick

Thanks for the reply. No, I didn't. I'm doing that now. Holy cow, there's a never-ending list of prompts to fix this and that.

It finally finished. I'll try to boot it.

I will use a USB 2.0 cable so the USB 3.0 ports wil be converted to USB 2.0. It's slower, but I've had luck with that trick in the past.

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#4 2020-11-20 18:57:42

nobodyuknow
Member
Registered: 2017-09-10
Posts: 74  

Re: SOLVED: Bad magic number in super-block

Yup, that fixed it. There was well over a hundred errors. Good thing the default is 'Y' so the Enter key is all one needs. Thanks again.

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#5 2020-11-21 16:51:52

PedroReina
Member
From: Madrid, Spain
Registered: 2019-01-13
Posts: 157  
Website

Re: SOLVED: Bad magic number in super-block

nobodyuknow wrote:

Good thing the default is 'Y' so the Enter key is all one needs

The "-y" option is handy too.

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