Greetings, I have created an IB interconnected SSD-backed centralized storage device running tgtd built from git master, custom 3.5.4 kernels on this storage array and all hypervisor hosts, and all IB and OVS related stuff built from master on their respective repos. I'm connecting to LVM LUNS served from this SSD array from the kvm hypervisor hosts using iSER. The kvm guests then use the iSER connected LUNS as their disks, attaching to them with virtio. First, the performance is absolutely fantastic and everything has been rock solid too. Thank you all for all of your hard work on this stuff! My question involves determining the best practice for delivering predictable and controllable IO QoS to the guests. I do not want a few IO hogs to slow everyone else down. Here's my thoughts on this at the moment: * Cap IO on hosts. On the hypervisor hosts, use cgroups to limit max IO per guest. I can easily set some arbitrary cap here, but it misses to point of maximizing resource usage and leveraging over-subscription. * Control IOPS per LUN on the array If I could understand how tgtd partitions/allocates resources per LUN, I could put each LUN in a cgroup on the array box as well, and control it from the array side (maybe this would be the only side I would need to control it from?). * Hybrid approach Some combination of array monitoring, guest IO monitoring and dynamic cgroup IO throttling on the hosts. How are people addressing this issue today? Any thoughts, ideas or pointers to existing work already addressing this issue <regardless of status> would be very much appreciated. Regards, Christopher Barry RJMetrics.com -- To unsubscribe from this list: send the line "unsubscribe stgt" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
