流媒体服务中即时响应的层次存储数据放置策略  

An Immediately Responsible Data Placement Method of Hierarchical Storage Management for Streaming Media Server

作　　者：徐尧强[1] 邢春晓[1] 周立柱[1] 

机构地区：[1]清华大学计算机科学与技术系,北京100084

出　　处：《计算机科学》2004年第9期23-25,28,共4页Computer Science

基　　金：国家重点基础研究发展规划资助项目(G1999032704)

摘　　要：为了获得较高的性能价格比,流媒体服务器通常采用层次存储技术。由于三级存储设备的机械特性,访问层次存储系统(HSM)中的数据需要很长的响应时间。本文提出了具有即时响应性能的数据放置方法:把流媒体对象特定长度的头部数据预先放置在磁盘上,而数据请求首先从HSM的磁盘上得到响应,在读取磁盘数据期间进行三级存储设备的准备。在特定的头部数据长度以及读取算法下,可以消除访问三级存储设备需要的等待时间。本文给出了此头部数据长度的计算方法以及HSM的数据读取算法。仿真试验表明,只需较小的存储代价,就可以使得HSM系统的响应时间大大降低,而且数据具有良好的连贯性,从而提高了整个系统的性能。Hierarchical storage technology is used in media servers to get high performance/cost ratio. However,in traditional hierarchical storage system (HSM),the data,say a movie,is usually placed wholly in a tertiary storage device. Thus,the response time to user's request will be too long to be satisfactory. This paper presents a new data placement method based on prearrangement strategy in HSM for streaming media server. By prearranging the head part of media objects with specified length on disk,streaming data accesses can get immediate response,and in the meantime,tertiary storage device can be ready for continuous access. The paper gives a method to calculate the head data length of media objects and an algorithm to read data in HSM. Simulation result shows that with a low disk storage cost ,the response time of the HSM system can be reduced to a large extent ,and the performance of the whole system is enhanced significantly.

关 键 词：存储设备 磁盘数据 数据读取 数据请求 流媒体服务器 存储系统 存储数据 HSM 响应时间 特定 

分 类 号：TP333[自动化与计算机技术—计算机系统结构] TP393[自动化与计算机技术—计算机科学与技术]