Hi All, I am setting the value for "read_bytes_sec" using the following API code virDomainSetBlockIoTune(dom, "/mnt/tmpsdb/FileVM1", parainfoPtr, nparams, 2); I am succesfully able to set this value and i can read it back using the API virDomainGetBlockIoTune(dom,"/mnt/tmpsdb/FileVM1",parainfoPtr,&nparams,2); But after setting this value when i shutdown my VM and start it again I am getting following error - ibvirtError: internal error Process exited while reading console log output: qemu-system-x86_64: -drive file=/mnt/tmpsdb/FileVM1,if=none,id=drive-ide0-1-1,format=raw,bps_rd=1048576: Invalid parameter 'bps_rd' Note - when i see dumpxml of the VM following lines are got added after setting the iotunes for read_bytes_sec <iotune> <read_bytes_sec>1048576</read_bytes_sec> </iotune> Please help me. Also i wanted to know whether we can set block IO tune for a VM using the above API. Is it same as the IO throttling provided by cgroup?