A record and file partitioning model

Abstract

One of the main objectives in the design of a file system is the reduction of storage and data transfer costs. This paper presents a model in which several requests access the file system, and each request requires information from one or more variable length data-items. The probabilities of access and the distribution of each data-item's length are assumed to be known, and to be mutually independent. The file system uses one or more storage devices, and each record may be partitioned into subrecords that are stored on different devices. One of the subrecords is designated as the primary record; when a request for a record is made, the primary record is first accessed, and other sub-records are accessed only if the pertinent information is not stored in the primary record. The model that is presented in this paper, both as a nonlinear programming model and a mixed integer programming model, is a very general one; several types of file systems may be derived from it by an appropriate selection of its parameters. This model has already been used in the optimization of library routines' storage at a large scale operating system.