Data management requirements: The similarity of memory management, database systems, and message processing

Abstract

Memory management, database management, and message processing have in the past been defined in a relatively narrow way. With memory management the problem was to obtain cost effective use of real memory. Given a multiprogrammed environment, virtual memory systems allowed more effective use of expensive real memory. Memory management has become even more important with the development of very large and complex memory hierarchies. Database management systems were developed to allow the more effective use, sharing, and control of data resources - objectives which operating systems had previously provided for hardware resources. The driving force behind message processing has been the increased use of data communications and computer networks. This paper will consider the basis of the overlap in these areas, their common data management functions. Data management, as defined in this paper, includes the locating, routing, moving, and translating of data resources and the locating, reserving, and releasing of physical resources, i.e., primary and secondary storage. The analysis performed in this paper is essential because of trends in computer architecture discussed below. Early hardware was designed for general purpose environments with software used to tailor it to specific applications. However, according to Gagliardi9 future systems will consist of a set of subsystems, including a storage subsystem at the core surrounded by computational, spooling, and communications subsystems. The computational subsystem is the traditional “number cruncher” part of the system. The spooling subsystem provides the I/O interface between the system and the outside world. The communications subsystem links the various subsystems together and provides an interface to the rest of the network if the system is part of a larger distributed system. The storage subsystem consists of all the system's storage resources and their control processes. It controls all levels of the system memory and storage hierarchy. The storage subsystem controls the allocation of the physical storage resources and the movement of the data resources through the system. Depending on how these resources are used, they may be non-conserved or conserved, and if conserved, either serially reusable or sharable. Physical and data resources may be located, and if necessary reserved, independently or jointly.