Umount: device busy

Latest response

Hello,

I have a problem with a file system that I cannot unmount:
[s1: ~]# umount /root/backup
umount: /root/backup: device is busy.
(In some cases useful info about processes that use
the device is found by lsof(8) or fuser(1))
[s1: ~]#

I have tried to find who is using it, but neither lsof nor fuser does not show any process using the file system:
[s1: ~]# fuser /root/backup
[s1: ~]# fuser -c /root/backup
[s1: ~]# lsof | grep backup
[s1: ~]#
I have checked the /proc/mounts to see if there is any mount which would use a mount point below this one, but there is none.

Now I can reboot the system to have that mount gone, but what can be done if reboot is not an option? Where should I look for its usage.
The device that is mounted here is an LVM snapshot which I'm using to backup a volume, I don't know if this makes any difference.

Thank you in advance for your answers.

Responses

Hi Pascal,

The filesystem you're trying to unmount, isn't it by any chance mounted over NFS? A broken connection would explain the problem.

Anyway, you can try to use either the -f (--force) option to unmount the filesystem no matter what, or the -l (--lazy) option to remove the filesystem from the file hierarchy (it will be 'really' unmounted when it stops being busy).

Hi Robert,

Unfortunately it is not NFS. I know about umount -f for nfs, But is not my case.
Regarding umount -l, that in my opinion is a very dangeros option when somabody has a cluster or a shared storage. One could by mistake think that the filesystem is unmounted and can mount it on an other node .... Anyway for me it is not an option as my goal is to destroy the device which is mounted (it is an LVM snapshot).

Kind regards,

Close

Welcome! Check out the Getting Started with Red Hat page for quick tours and guides for common tasks.