I'm trying to understand how does using CFQ affects the "Nosy Neighbor" problem. I'll ask it a bit naively, can a "Nosy Neighbor" even exist when using CFQ? Isn't that CFQ should make sure all processes(VMs) get fair slices of storage time? If so, how can one VM I/O interfere with another's VM I/O when CFQ is being used?
Environment is CentOS6.5+OpenStack+KVM+Ceph