root@host# vzctl set 777 --iolimit 3M --save
Setting iolimit: 3145728 bytes/sec
CT configuration saved to /etc/vz/conf/777.conf
root@host# vzctl enter 777
root@CT:/# cat /dev/urandom | pv -c - >/bigfile3
39.1MB 0:00:10 [ 3MB/s] [ <=> ]
^C