When I tried starting a OpenVZ container on our node, I faced this error below.
QuoteCan't umount : Device or resource busy
Make sure if you have any other SSH connections open, or any other connection that may be causing the problem. most of the time it's just an SSH connection you still have open.
If that doesn't working, perform the steps below.
Shutdown the VPS/container by logging into it OR from the node/host.
By logging into the VPS
Quote# shutdown -h now
By logging in the node
Quote# vzctl stop 999
Now, try to unmount it with command below.
Quote# vzctl umount 999
Finally, check if the VPS is in mounted state
Quote# cat /proc/mounts | grep 999
If it shows to be mounted, umount the directories that shows in the output.
Note: Make sure you replace 999 with actual container ID.