Cannot find mounted disk : "already mounted or mount point busy."

Super User Asked by eClapton on October 28, 2020

Im struggling to find why I cannot access a seagate drive.
System says it’s mounted:

[email protected]:~$ sudo mount /dev/sdb1 /mnt/disk2/
mount: /mnt/disk2: /dev/sdb1 already mounted or mount point busy.

But cannot umount it:

[email protected]:~$ sudo umount -f /dev/sdb
umount: /dev/sdb: not mounted.

And also, it is not present in /etc/mtab:

[email protected]:~$ cat /etc/mtab | grep sd
cgroup2 /sys/fs/cgroup/unified cgroup2 rw,nosuid,nodev,noexec,relatime,nsdelegate 0 0
nfsd /proc/fs/nfsd nfsd rw,relatime 0 0
/dev/sda1 /srv/dev-disk-by-label-uno ext4 rw,relatime,jqfmt=vfsv0,usrjquota=aquota.user, 0 0
/dev/sda1 /export/PLEX ext4 rw,relatime,jqfmt=vfsv0,usrjquota=aquota.user, 0 0

Only my first drive sda is showing

[email protected]:~$ dmesg | grep sdb
[    5.014287] sd 1:0:0:0: [sdb] 976773168 512-byte logical blocks: (500 GB/466 GiB)
[    5.014358] sd 1:0:0:0: [sdb] Write Protect is off
[    5.014373] sd 1:0:0:0: [sdb] Mode Sense: 00 3a 00 00
[    5.014487] sd 1:0:0:0: [sdb] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
[    5.041141] sd 1:0:0:0: [sdb] Attached SCSI disk

Tried fsck’ing the drive, but it won’t let me… as it says is in use

[email protected]:~$ sudo  fsck -f /dev/sdb
fsck from util-linux 2.33.1
e2fsck 1.44.5 (15-Dec-2018)
/dev/sdb is in use.
e2fsck: Cannot continue, aborting.

fdisk -l output:

[email protected]:~$ sudo fdisk -l
Disk /dev/sdb: 465,8 GiB, 500107862016 bytes, 976773168 sectors
Disk model: ST3500820AS     
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: 91A91874-7314-4C83-8061-0904AE8BF0B1

Device     Start       End   Sectors   Size Type
/dev/sdb1   2048 976773134 976771087 465,8G Linux filesystem

Any ideas how to

  • Force mount, umount?
  • Force fsck, as I doubt on the drive’s integrity
  • Find out where is it mounted? (even I don’t think so)

Thank you for your help

EDIT: Tried with the –bind option, but it answers:

mount(2) system call failed: not a directory

Dont understand…

EDIT 2: After mounting successfully, now I cannot write to it… dmesg shows a myriad of:

[ 7822.964530] EXT4-fs (sdb1): I/O error while writing superblock
[ 7822.964543] EXT4-fs error (device sdb1) in ext4_convert_unwritten_io_end_vec:4798: Journal has aborted
[ 7822.964605] EXT4-fs (sdb1): I/O error while writing superblock
[ 7822.964612] EXT4-fs (sdb1): failed to convert unwritten extents to written extents -- potential data loss!  (inode 12582922, error -30)

and then:

[ 7822.965799] JBD2: Error -5 detected when updating journal superblock for sdb1-8.
[ 7822.972166] EXT4-fs (sdb1): I/O error while writing superblock
[ 7822.972182] EXT4-fs error (device sdb1): ext4_journal_check_start:83: Detected aborted journal
[ 7822.972187] EXT4-fs (sdb1): Remounting filesystem read-only
[ 9018.053019] scsi_io_completion_action: 25 callbacks suppressed

Does this mean I can finally throw away the drive?


Oh! there’s this big known problem

Does anybody know if I can update the firmware from command line, or USB external? I have this external box for SATA/USB connection.

[Armbian Debian buster 10 Helios64 NAS Linux helios64 5.8.14-rockchip64]

2 Answers

The Conclusion for this case is, as anyone who reads the complete post can easily find out: the drive was faulty due to buggy firmware, acknowledged by Seagate in the link provided in EDITED answer #3. Thank to all those who have not contributed with any answer, but have pointed out every minor inaccuracies in my informations/formattting/English usage.

Bye bye superuser.

Answered by eClapton on October 28, 2020

You're trying to mount /dev/sdb1 but unmount /dev/sdb. These are not the same

Oh. Your sudo fsck -f /dev/sdb - be very glad it refused to do that. You would have destroyed the (mounted) filesystem if you had got the partition sdb1 rather than the disk sdb.

Answered by roaima on October 28, 2020

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