Cicada: Introducing Predictive Guarantees for Cloud Networks

In cloud-computing systems, network-bandwidth guarantees have been shown to improve predictability of application performance and cost. Most previous work on cloud-bandwidth guarantees has assumed that cloud tenants know what bandwidth guarantees they want. However, as we show in this work, application bandwidth demands can be complex and time-varying, and many tenants might lack sufficient information to request a guarantee that is well-matched to their needs, which can lead to over-provisioning (and thus reduced cost-efficiency) or under-provisioning (and thus poor user experience). We analyze traffic traces gathered over six months from an HP Cloud Services datacenter, finding that application bandwidth consumption is both time-varying and spatially inhomogeneous. This variability makes it hard to predict requirements. To solve this problem, we develop a prediction algorithm usable by a cloud provider to suggest an appropriate bandwidth guarantee to a tenant. With tenant VM placement using these predictive guarantees, we find that the inter-rack network utilization in certain datacenter topologies can be more than doubled.