磁带库系统的随机I/O调度算法

由于磁带库随机存取的性能很差,需要研究有效的随机I/O调度策略和算法以改善其在线存取的效率.对已有调度算法进行了分类、提炼和总结,利用仿真实验对静态调度、动态调度和基于复制的调度算法进行了深入研究,讨论了影响各种算法有效性的因素.针对已有算法在较重的负载条件下使系统性能急剧恶化的问题,还提出并研究了一种基于效益-代价均衡的调度算法.该算法引入效益-代价加权的概念,通过调节不同负载下的效益-代价加权比,极大地改善了已有算法在重负载下的有效性.该项研究为设计海量存储系统中的自适应调度算法提供了重要依据.

Random I/O Scheduling Algorithms in Online Tape Library Systems

Since the tape libraries have very poor random access performance, it is critical to study random I/O scheduling strategies and algorithms in order to improve the performance of tape library. In this paper, the existing scheduling algorithms are summarized first, and then the analytical results of the effectiveness of static scheduling, dynamic scheduling and replication-based scheduling are presented through simulations. In particular, a benefit-cost-based scheduling algorithm is given, which aims to improve the effectiveness of exosting scheduling algorithms under heavy workloads by tuning the weight ratio of cost and benefit of scheduling policies according to workloads.This algorithm is significantly effective under heavy workloads.The research of this paper forms the basis of the design of adaptive scheduling algorithms that can be used in massiv storage systems.