VirtualKnotter: Online virtual machine shuffling for congestion resolving in virtualized datacenter

Our measurements on production datacenter traffic together with recently-reported results (Kandula et al.) [1] suggest that datacenter networks suffer from long-lived congestion caused by core network oversubscription and unbalanced workload placement. In contrast to traditional traffic engineering approaches that optimize flow routing, in this paper, we explore the opportunity to address the continuous congestion via optimizing VM placement in virtualized datacenters. To this end, we present VirtualKnotter to reduce congestion with controllable VM migration traffic as well as low migration time, which includes an online VM placement algorithm and an efficient VM migration scheduling algorithm. Our evaluation with both real and synthetic traffic patterns shows that VirtualKnotter performs close to the baseline algorithm in terms of link unitization, with only 5-10% migration traffic of the baseline algorithm. Furthermore, VirtualKnotter decreases link congestion time by 53% for the production datacenter traffic.