In this paper, we consider the accessing of batched requests in a linear storage medium. The batch size is assumed fixed and the access probabilities of individual records known. For a given arrangement of records in the storage, we consider the problem of read/write head scheduling to minimize the expected access time for a batch measured in terms of the distance traveled by the head. In the first part of the paper, several simple algorithms are proposed, analyzed and compared. The effect of different record arrangements is also discussed. In the second part of the paper, a family of algorithms called B-optimal rules are described. When B is $\infty$, an Batched processing   expected access time   read/write head scheduling   minimization of disk seek time   linear storage medium   near-optimal algorithms   optimal algorithms   scheduling algorithms   -optimal algorithms   -optimal algorithms   organ-pipe arrangement of records   discrete dynamic programming  

We consider the problem of placing records in a 2-dimensional storage array so that expected distance between consecutive references is minimized. A simple placement heuristic which uses only relative frequency of access for different records is shown to be within an additive constant of optimal when distance is measured by the Euclidean metric. For the rectilinear and maximum metrics, we show that there is no such heuristic. For the special case in which all access probabilities are equal, however, heuristics within an additive constant of optimal do exist, and their implementation requires solution of differential equations for which we give numerical solutions.