I have an ext4 filesystem mounted on
/var/lib/docker, using Ubuntu 14.04.
umount /var/lib/docker and got:
umount: /var/lib/docker: device is busy.
I had already shut down docker with
service docker stop and
ps aux showed no processes.
The strange thing is that both
fuser -M /var/lib/docker and
lsof +f -- /var/lib/docker show no processes with files open.
This doesn't happen on 40+ other servers with same setup, and I have just noticed this.
A reboot fixed this - curious if anyone has some idea what's going on, or any other ways to investigate if it recurs.
- Docker (1.11.2) had been using aufs as the overlay filesystem for its containers, on top of this FS - but all containers and Docker processes were killed before the
- Kernel details:
Linux node05 4.4.0-38-generic #57~14.04.1-Ubuntu SMP Tue Sep 6 17:20:43 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux
Possibly related questions:
UPDATE - recurrence on another server
This recurred on a different server with very similar configuration, in same situation - have shut down docker, and can't
umount /var/lib/docker because it's "busy".
lsof show no processes with files open on the docker FS.
mount | grep aufs showed no aufs filesystems
df -h| grep docker showed two Docker managed filesystems mounted underneath the /var/lib/docker directory (
lsof doesn't show these, it seems).
However, unmounting these two filesystems didn't help with this problem.
The only workaround remains to edit
/etc/fstab to temporarily comment out the
/var/lib/docker filesystem, then reboot the server so
/var/lib/docker is not mounted.