OpenVZ: Can’t umount (unmount) device or resource busy

first check to make sure you don’t have any other SSH connections open, or any other connection that may be causing the problem. 99% of the time it’s just an SSH connection you still have open.

If that doesn’t work, go ahead and login to the container and shutdown:
shutdown -h now

Or from the main node:
vzctl stop 100

Once the container is shutdown, attempt to unmount it and see if it throws any errors:
vzctl umount 100

If you still can’t unmount it, try these to see if anything stands out:
ps aux|grep 100

lsof |grep 100

lsof |grep 'root/100'

The final check which ended up being where I found my problem is to run:
cat /proc/mounts |grep 100

Here’s what I ended up finding:
/var/lib/vz/private/100 /var/lib/vz/root/100 simfs ro,relatime 0 0
/var/lib/vz/private/100 \040(deleted)/var/lib/vz/root/100/var/named/chroot/etc/named.rfc1912.zones simfs ro,relatime 0 0
/var/lib/vz/private/100 \040(deleted)/var/lib/vz/root/100/var/named/chroot/etc/named.iscdlv.key simfs ro,relatime 0 0
/var/lib/vz/private/100 \040(deleted)/var/lib/vz/root/100/var/named/chroot/etc/named.root.key simfs ro,relatime 0 0


Turns out it there was still active in read only mode. And the simple way to fix that was:
umount -l /var/lib/vz/root/100

Hope this helps, good luck!

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OpenVZ: Error booting containter: Device or resource busy


I had same problem and have no idea to solve it correctly, but here is at least some solution:
You have to change mount point for your VE (example 102) from /var/lib/vz/root/102 to (for example) /var/lib/vz/root/YAHOO/102
mkdir -p /var/lib/vz/root/YAHOO/102
and in the file /etc/pve/openvz/102.conf (or /etc/vz/conf/102.conf) replace string VE_ROOT="/var/lib/vz/root/$VEID" to VE_ROOT="/var/lib/vz/root/YAHOO/$VEID"

It is ugly, but working.