Network-centric Performance Improvement for Live VM Migration

Live Virtual Machine (VM) migrations are an important tool that is used in modern data centers in order to e.g. Consolidate server racks for maintenance or optimize VM placements across physical hosts. However, live VM migration causes a lot of network stress due to the potential large volume of data that is transmitted between the physical hosts, which may negatively impact other latency sensitive VM to VM traffic. As VM downtime and the time to migrate depend on the allocated resources for migration traffic, it is important to manage the network resources for live VM migration traffic. In this work, we improve the performance for both live VM migration traffic and VM to VM communication using three strategies. First, we take advantage out of the path diversity available in modern data centers and utilize multipath TCP (MPTCP) for live VM traffic. Second, we implement flexible use of queue management strategies such as FQ CODEL or Hierarchy Token Bucket (HTB). Finally, we orchestrate the process into Open Stack Neutron and connect it together with an SDN control application, which runs on Open Daylight. An extensive evaluation in our Open Stack test bed using different VM workload patterns and VM sizes shows, that FQ CODEL can bring down VM to VM latency during ongoing migrations while MPTCP effectively aggregates bandwidth of multiple paths to reduce live VM migration latency and downtime.