Range-BW: I/O Scheduler for Predicable Disk I/O Bandwidth

Disk I/O has been considered as serious bottleneck point in server system for a long time. In serious workload situation that we run several services in same system, we don't make sure important service has more I/O bandwidth than others and it causes performance degradation of the important service. So, they should be treated with discrimination in I/O resource management to guarantee the performance stability of each service. In this paper, we propose the new I/O controller, Range-BW, to satisfy the upper requirement. The proposed I/O controller supports the range bandwidth including the two concepts, guaranteeing of minimum bandwidth and limitation of maximum bandwidth in aspect of service. These features enable the administrator to use efficiently the limited I/O resources and to control it dynamically and freely according to the priority of the service. So, Range-BW is useful to maintain the stable performance of the specific application or service.