You can try running fsck without auto fix to see what might be wrong.

$ fsck -n
fsck from util-linux 2.27.1
e2fsck 1.42.13 (17-May-2015)
Warning! /dev/sda5 is mounted.
fsck.ext4: Permission denied while trying to open /dev/sda5
You must have r/o access to the filesystem or be root

Did not try as root. How do I get it to only check sdb?

$ sudo fsck -n UUID=9983149b-3a05-462b-96a6-939625e6c7b6
[sudo] password for tom:
fsck from util-linux 2.27.1
e2fsck 1.42.13 (17-May-2015)
Superblock has an invalid journal (inode 8).
Clear? no

fsck.ext4: Illegal inode number while checking ext3 journal for /dev/sdb6

/dev/sdb6: ********** WARNING: Filesystem still has errors **********

Since you posted a reinstall I assume you have a decent backup or don't care about the date. You can try to see if running fsck for real will fix the problem but suspect it may work.

In post #9, you showed the command you tried to use to mount sdb6. You were missing a mount point so that will never work.

The output of the df -h command you posted earlier clearly shows that as sdb1. Do you have anything on sdb6, a filesystem or data of any sort.

You need to run fsck as root, see the link below as this is very basic. You specify it in the command the same way you need to specify a mount point when trying to mount a partition. Since you failed to specify a partition/device, it tried to run on sda5 which is your root "/" filesystem partition and it failed because it was mounted.

https://www.tecmint.com/fsck-repair-...rors-in-linux/

I have several hundred GB of files



Ran fsck -n
$ sudo fsck -n UUID=9983149b-3a05-462b-96a6-939625e6c7b6
[sudo] password for tom:
fsck from util-linux 2.27.1
e2fsck 1.42.13 (17-May-2015)
Superblock has an invalid journal (inode 8).
Clear? no

fsck.ext4: Illegal inode number while checking ext3 journal for /dev/sdb6

/dev/sdb6: ********** WARNING: Filesystem still has errors **********

$ sudo umount /dev/sdb
umount: /dev/sdb: not mounted

~ $ sudo fsck /dev/sdb
fsck from util-linux 2.27.1
e2fsck 1.42.13 (17-May-2015)
/dev/sdb is in use.
e2fsck: Cannot continue, aborting.

How is sdb in use if it is unmounted?

$ sudo umount /dev/sdb1
tom@tom-Inspiron-1520120 ~ $ sudo fsck /dev/sdb1
fsck from util-linux 2.27.1
e2fsck 1.42.13 (17-May-2015)
/dev/sdb1 has unsupported feature(s): metadata_csum
e2fsck: Get a newer version of e2fsck!

~ $ sudo apt-get install e2fsck
Reading package lists... Done
Building dependency tree
Reading state information... Done
E: Unable to locate package e2fsck

$ sudo apt-get install e2fsck
Reading package lists... Done
Building dependency tree
Reading state information... Done
E: Unable to locate package e2fsck

https://ext4.wiki.kernel.org/index.p...data_Checksums

According to some information I found e2fsck did not support metadata checksums until version 1.43. The simplest might be to boot from a live Mint 20 and try again.

e2fsck is part of the e2fsprogs package.

Booted 20.1 Live.

$ sudo fsck -n /dev/sdb6
fsck from util-linux 2.34
e2fsck 1.45.5 (07-Jan-2020)
Superblock has an invalid journal (inode 8).
Clear? no

Journal superblock is corrupt.
Fix? no

fsck.ext4: The journal superblock is corrupt while checking journal for /dev/sdb6
e2fsck: Cannot proceed with file system check

/dev/sdb6: ********** WARNING: Filesystem still has errors **********


sudo fsck -n /dev/sdb1
fsck from util-linux 2.34
e2fsck 1.45.5 (07-Jan-2020)
/dev/sdb1: clean, 353750/1831424 files, 2151828/7323974 blocks

mint@mint:~$ umount /dev/sdb
umount: /dev/sdb: not mounted.
mint@mint:~$
mint@mint:~$ sudo fsck -n /dev/sdb
fsck from util-linux 2.34
e2fsck 1.45.5 (07-Jan-2020)
Warning! /dev/sdb is in use.
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/sdb

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/sdb

Your using the id for the entire drive and not the bad filesystem i.e. /dev/sdb6.

The -n option runs the checks but does not fix.

mint@mint:~$ sudo fsck -y /dev/sdb6
fsck from util-linux 2.34
e2fsck 1.45.5 (07-Jan-2020)
Superblock has an invalid journal (inode 8) ...

Free inodes count wrong (41948175, counted=42005939).
Fix? yes

Padding at end of inode bitmap is not set. Fix? yes


/dev/sdb6: ***** FILE SYSTEM WAS MODIFIED *****
/dev/sdb6: 35405/42041344 files (0.9% non-contiguous), 32013233/168162048 blocks

mint@mint:~$ sudo fsck -n /dev/sdb6
fsck from util-linux 2.34
e2fsck 1.45.5 (07-Jan-2020)
/dev/sdb6: clean, 35405/42041344 files, 32013233/168162048 blocks


Will reboot20.1

Waiting in anticipation...

Booted to 20.1 to login. Entered password. After a while the login prompt reappears like before.

I should of suggested trying to mount it from the live version to actually see if it was "working"

can do.