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本文对双头镜像磁盘系统模型进行实时扩展，并提出了三种实时调度算法：最早截止期优先算法（ＥＤＦ），可满足的最早截止期优先算法（Ｆ－ＥＤＦ）和忽视超时限请求算法（ＩＧＭ－ＥＤＦ）．这三种算法充分考虑了Ｉ／Ｏ请求的截止期限，使双头镜像磁盘系统能更好地满足实时需求．在进行了性能模拟后，发现实时调度算法比非实时算法能更好地满足实时Ｉ／Ｏ请求的时限要求．三种实时调度算法中，适用于硬实时应用的ＩＧＭ－ＥＤＦ的性能最好，Ｆ－ＥＤＦ算法的性能次之，它适用于软实时环境．
In this paper, real-time extension of the double-headed mirror disk system model is proposed and three real-time scheduling algorithms are proposed: the first deadline first algorithm (EDF), the satisfiable earliest deadline first algorithm (F-EDF) IGM-EDF). These three algorithms take full account of the deadline for I / O requests, enabling a two-headed mirror disk system to better meet real-time requirements. After performing the performance simulation, we found that the real-time scheduling algorithm can better meet the time-limit requirements of real-time I / O requests than non-real-time algorithms. Among the three real-time scheduling algorithms, IGM-EDF is the best one for hard real-time applications, and F-EDF algorithm is second, which is suitable for soft real-time environment.