摘要
研究I/O负载特征,建立恰当的I/O负载模型,对存储系统的设计、优化和评估有重要的意义.通过研究发现,许多I/O到达模式和访问模式在不同尺度下都具有相似的"突发性".而传统的泊松模型不具有这种特点,因此,研究者提出用自相似模型来描述I/O负载.此外,虽然自相似模型能够较好地描述I/O负载的长相关性,但是,它们却难以描述较小尺度上的局部奇异行为.于是,一些研究者提出用多分形模型来弥补这一缺陷.总结了目前I/O负载自相似研究的成果,分析了I/O负载自相似的研究现状,探讨了I/O负载自相似研究的发展趋势.通过分析得出,目前,自相似的评估问题还未被完全解决,I/O负载的自相似性在存储系统设计中的意义的研究还需要更深入,另外,如何建立更准确高效的I/O负载多分形模型也是一个还需要更深入研究的方面.
In order to optimize the performance of storage systems and lighten the bottleneck effects of disk-based storage systems in computer systems, the characteristics of I/O workloads need to be studied, so as to create accurate models to describe them. Recently, researchers have found that in many I/O workloads, arrival patterns and access patterns have similar burstiness at different scales. However, traditional Poisson models cannot describe this kind of burstiness. Some researchers then propose self-similarity models to describe I/O workloads. In addition, though self-similarity models describe long-range dependence （LRD） in I/O workloads very well, they are unable to describe local variations and irregularities at relatively small scales. Therefore, some researchers propose multifractal models to make up for the defects of self-similarity models. In this paper, the definitions of self-similar stochastic processes and the estimation methods of self-similarity are first introduced. The self-similarity in I/O workloads is then discussed. After that, several self-similarity models of I/O workloads, such as Sup-FRP models, ON/OFF models, M/G/∞ models, and so on, are introduced. Finally, two multifractal models of I/O workloads, b-models and PQRS models are presented. After analyzing the status of studies, several conclusions are drawn： （a） Self-similarity estimation is still a hard problem that has not been completely solved. This is an aspect that needs further study; （b） From the perspective of storage system design, the significance of self-similarity in I/O workloads is still an important aspect that needs further study; and （c） How to create more accurate multifractal models is also an aspect that needs further study.
出处
《计算机研究与发展》
EI
CSCD
北大核心
2008年第6期1072-1084,共13页
Journal of Computer Research and Development
基金
国家自然科学基金项目(60473101)
国家"九七三"重点基础研究发展规划基金项目(2004CB318205)
国家教育部新世纪优秀人才支持计划基金项目(NCET-05-0067)
高等学校博士学科点专项科研基金项目(20070003092)~~
