A network bandwidth computation technique for IP storage with QoS guarantees

Abstract

IP storage becomes more commonplace with the prevalence of the iSCSI (Internet SCSI) protocol that enables the SCSI protocol to run over the existing IP network. Meanwhile, storage QoS that assures a required storage service for each storage client has gained in importance with increased opportunities for multiple storage clients to share the same IP storage. Considering the existence of other competing network traffic in IP network, we have to provide storage I/O traffic with guaranteed network bandwidth. Most importantly, we need to calculate the required network bandwidth to assure a given storage QoS requirement between a storage client and IP storage. This paper proposes a network bandwidth computation technique that not only accounts for the overhead caused by the underlying network protocols, but also guarantees the minimum data transfer delay over the IP network. Performance evaluations with various I/O workload patterns on our IP storage testbed verify the correctness of the proposed technique; that is, allocating a part (0.6-20%) of the entire network bandwidth can assure the given storage QoS requirements.