Space management system for data files having shared access

Abstract

A Space Management System for a Data Access System of a File Access Processor for servicing requests from a set of Application Support Processors, which can exist in a global network, with each Application Support Processor sharing access to data in files stored by the File access Processor. The File Access Processor manages access to a set of data files and information about files held in file directories, which allow for managing file collections, can relate to each other hierarchically, and may be shared. Each Application Support Processor also maintains therein an internal cache of file information to improve performance by reducing communications required with the File Access Processor for informatin about files. The File Access Processor provides the Application Support Processors with information for updating and maintenance of local caches of directory and file description information through a centralized accumulation and distribution of cache change notifications. The Space Management System manages file space assigned to each Application Support Processor and supports the space management functions of, adding space, deleting space, setting thresholds for limit warnings, querying space, charging space used, warning notifications, crediting space freed, and permitting file spaces to be shared by more than one application suppoort processor.