I'm using cgroups to cap disk IO that a VM does by using libvirt's support for cgroups.
So, I'm getting the major/minor number of the device from a 'ls -lL' on the drive where the '.img' file for the VM is located.
However, when I try to cap the IO, I get an error -
root@Silver:/sys/fs/cgroup/blkio/sysdefault/libvirt/qemu/debian1# echo "8:6 1048576" > blkio.throttle.read_bps_device
bash: echo: write error: No such device
Any idea what I'm doing wrong?