Controlling Network Bandwidth to Support Storage QoS

In network storage environments, it is difficult that a network storage system satisfies each client's service requirements because the specification of QoS requirements is presented as {request size, IOPS, response time ...}, which is used in the existing storage QoS area. Since network storage system has two resources: storage and network, storage QoS requirements to manage two resources effectively, must be specified. In particular, our study considers the TCP/IP-based network. In this paper, to support each client's storage QoS requirements easily, the specification of each client's storage QoS requirements will be presented in terms of bandwidth. The network bandwidth of a storage server must be managed because the storage service can be affected by the network bandwidth. This paper presents the QoS framework regulating the network bandwidth of the storage server to realize the storage performance isolation among the clients. The proposed framework monitors the network resource and the storage resource periodically, identifies the bottleneck resource, selects victims among clients competing for the bottleneck resource and regulates the network bandwidth given to victims to satisfy a client's storage QoS requirements. We implemented the QoS-enabled network storage using the iSCSIprotocol.