My Linux server (Centos 7.5) is in a strange state with USB drives. When I try to mount a partition on a USB drive to a newly created mount point I get the error

mount: /dev/sdd1 is already mounted or /mnt/foo busy.

/mnt/foo is a newly created mount point, so it should not be busy. Which implies that /dev/sdd1 is already mounted. However, when I try to unmount it I get the error

umount: /dev/sdd1: not mounted

The system appears to be in some confused state where I can neither mount or unmount a USB drive?

Is there some command I can run to get things right so that I can mount a USB drive? I don't want to have to reboot the system. The details are shown below. Thanks

# lsblk
sdd                 8:48   1  29.8G  0 disk
└─sdd1              8:49   1  29.8G  0 part
# mkdir /mnt/foo
# mount /dev/sdd1 /mnt/foo
mount: /dev/sdd1 is already mounted or /mnt/foo busy
# umount /dev/sdd1
umount: /dev/sdd1: not mounted

UPDATE: the USB storage subsystem seems to be in a bad state. When the USB drive is removed, the 'lsusb' output still shows the device. And when other USB drives are inserted, they don't show up at all. I tried to unload and reload the 'usb-storage' kernel module, but because it is in use it won't unload it.

I think this could be a firmware or hardware issue.

  • The output of cat /proc/mounts would be useful to include in your question.
    – kasperd
    Oct 25, 2018 at 15:31
  • Same problem here in a different context with /dev/sr0. Output of /proc/mounts shows: not mounted.
    – Regis May
    Jun 11, 2021 at 11:36

1 Answer 1


Try creating a new mount point instead of /mnt/Foo says "mounted OR busy"

May want to try with Sudo as well

  • I do create a new mount point each time, as the session transcript indicates. I am running the commands as root, so no need for sudo. Oct 22, 2018 at 23:58
  • You are right about not needing sudo; but yes it is advised to create a unique mount point for each path especially if a process is still holding the path Oct 23, 2018 at 0:01
  • The only time the or busy should show up is when the device is an LVM (or maybe a md) volume. It's perfectly possible to mount a new file system on /mnt/foo when a process has /mnt/foo open or if another device is already mounted there. Is /dev/sdd1 being scanned by fsck or an anti-virus at the time of the mount command?
    – doneal24
    Oct 23, 2018 at 1:24

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