A Non-partitioning File Assignment Scheme with Approximating Average Waiting Time in Parallel I/O System

As storage system runs an increasing variety of workload, there may be many file requests do not dispatch for a long time. The web clients who wait a long time will leave away. This paper presents a novel non-partitioning file assignment strategy called Static Approximate Fairness algorithm (SAF) in parallel I/O system. The SAF algorithm aims at obtaining approximate mean waiting time for disk file requests, as well as making load balancing in parallel I/O system. The approximate mean waiting time provides the same chance to serve different web clients. The technique we applied is referred to as open queuing network model. The SAF algorithm first selects files according to file load. Next, it assigns files to different disks until reaching their average load. The goal of fairness is obtained by assigning files to disks in terms of file load. Comprehensive experimental results indicated our new algorithm is superior to Sort Partition (SP) in terms of fairness.