I/O limits

The I/O limit feature is available in OpenVZ since kernel 2.6.32-042stab084.3 and vzctl 4.6. This feature allows to limit disk I/O bandwidth available to a container.

Example

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

Details

Limit works for reading and writing. There is also a burstable limit which allows 3x normal limit for a very short time.

See also

• vzctl(8), I/O scheduling
• OpenVZ blog: Yay to I/O limits!
• I/O priorities
• IO accounting