Proportional-share algorithms are designed to allocate an available resource, such as a network, processor, or disk, for a set of competing applications in proportion to the resource weight allotted to each. While a myriad of proportional-share algorithms were made for network and processor resources, little research work has been conducted on disk resources, which exhibit non-linear performance characteristics attributed to disk head movements. This paper proposes a new proportional-share disk-scheduling algorithm, which accounts for overhead caused by disk head movements and QoS guarantees in an integrated manner. Performance evaluations via simulations reveal that the proposed algorithm improves I/O throughput by 11–19% with only 1–2% QoS deterioration.