Quorum: Providing Flexible Quality of Service for Large-Scale Internet Services

In this paper we describe Quorum: a new non-invasive software approach to scalable quality-of-service provisioning that uses traffic shaping, admission control, and response monitoring at the borders of the Internet hosting site to ensure throughput and response time guarantees. We compare Quorum both to over-provisioning and to Neptune – a research and now commercially successful middleware system that implements QoS for Internet services. Our results show that Quorum can enforce the same QoS guarantees as Neptune for Neptune-enabled services, but without requiring the additional development overhead required by Neptune. We also detail Quorum’s flexibility by using it to provide QoS guarantees for an Internet service benchmark that is not ready to be used with Neptune or any other invasive software approach. In this case, Quorum achieves the same results a over-provisioning (which is the only other feasible solution) using one-half of the site resources.