| 摘要: |
| 文章给出一个实时非固定双头镜像磁盘系统的形式化模型.该磁盘模型中的每个双头磁盘都有两个相互独立的磁臂，能够独立地完成寻找磁道过程.针对该磁盘系统，文章研究了3种实时调度算法.模拟实验表明，“忽略超截止期调度算法”的性能最好，因为它忽略了对超截止期限实时请求的处理.文章同时分析了固定双头镜像磁盘与非固定双头镜像磁盘之间的性能差别.实验结果表明，由于非固定双头磁盘的两个磁头可以独立寻找磁道，因此非固定双头镜像磁盘的性能比固定双头镜像磁盘的性能要好. |
| 关键词: 非固定双头镜像磁盘，实时磁盘调度算法，I/O请求，模拟实验，性能评价. |
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| 基金项目:本文研究得到国防预研项目基金资助. |
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| Study of Real-time Disk Scheduling for Two-headed Mirrored Disk with Autonomous Heads |
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QIN Xiao,PANG Li-ping,HAN Zong-fen,LI Sheng-li
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| Abstract: |
| A real-time model for two-headed mirrored disks with autonomous heads is proposed in this paper. Two-headed disks (THD) in this system have two independent arms which can seek cylinder autonomously. Three real-time disk-scheduling algorithms are presented for such disk systems. According to simulation experiments, the algorithm which is called ignore missed deadlines (IGM-EDF) has the best performance, because IGM-EDF does not process those real-time requests which have missed deadlines. The comparison between two-headed mirrored disk with fixed heads(FTMD) and the disk system with autonomous heads (ATMD) is also analyzed in this paper. Because two heads in THD can seek cylinder independently, the performance of ATMD is better than that of FTMD. |
| Key words: Two-headed mirrored disk with autonomous heads, real-time disk scheduling, I/O request, simulation experiment, performance evaluations. |
