设磁盘上有n个文件f1, f2, …, fn,每个文件占用磁盘上的1个磁道。这n个文件的检索概率分别是p1, p2, …, pn,且p1+p2+…+ pn =1。磁头从当前磁道移到被检信息磁道所需的时间可用这2个磁道之间的径向距离来度量。如果文件fi存放在第i道上，1≦i≦n，则检索这n个文件的期望时间是对于所有的i < j, time+=pi*pj*d(i,j)。其中d(i,j)是第i道与第j道之间的径向距离|i-j|。

磁盘文件的最优存储问题要求确定这n个文件在磁盘上的存储位置,使期望检索时间达到最小。

-Documents n f1, f2, ..., fn, each file on the disk occupied by a track provided on the disk. The probability of the n retrieval documents are p1, p2, ..., pn, and p1+p2+ ...+ pn = 1. The time required to move the head of the subject is available information track radial distance between these two tracks from the current track to measure. If the file is stored in the i-th track fi, 1 ≦ i ≦ n, the time to retrieve a desired file which is n for all i < j, time+ = pi* pj* d (i, j). Where d (i, j) is the radial distance of the i channel between the channel and the j | ij |. Optimal disk file storage issues required to determine these n files on disk storage location, so expect the search time to a minimum.