In a former post, we know how to fix vzquota: (error) Quota on syscall: Device or resource busy

Here's another very common OpenVZ error message:

Code:
[root@vz-ms ~]# vzctl start 7
Warning: configuration file for distribution cern-4-i386-minimal not found default used
Starting container ...
vzquota : (warning) Quota is running for id 7 already
Container is mounted
Adding IP address(es): 192.168.8.7
vps-net_add ERROR: Unable to add route /sbin/ip route add 192.168.8.7 dev venet0 
Container start failed
Stopping container ...
Container was stopped
Container is unmounted
The root cause is very simple... I guess you simply haven't started vz service, thus venet0 device is not up and running in the host system. By fixing it, you need to run
Code:
# /etc/init.d/vz start
before starting VEs.
Make sure you have also configured /etc/sysctl.conf according to installation HOWTO.