vzquota : (error) Quota on syscall for id XXX: Device or resource busy

If you get this error, it means that some file from VE private area was in use. Here XXX is the vps id.

#vzctl restart XXX
Restarting container
Starting container...
vzquota : (error) Quota on syscall for id XXX: Device or resource busy
vzquota : (error) Possible reasons:
vzquota : (error) - Container's root is already mounted
vzquota : (error) - there are opened files inside Container's private area
vzquota : (error) - your current working directory is inside Container's
vzquota : (error) private area
vzquota : (error) Currently used file(s):

To fix this, run the following command and find out if any process using the files in VE private area.

# lsof 2> /dev/null | egrep '/vz/root/XXX | /vz/private/XXX'

If any process lists,  kill those process and try start the VPS again.

And you should now able to start the vps without any issue...!!