Abstract: A data storage management system and method includes a physical storage, an interim storage which acts as a virtual storage to the physical storage, and a manager. The manager assigns a first interim storage portion to the first computer for a time duration in lieu of the physical storage upon receipt of an allocation request from the first computer requesting allocation of data storage space on the physical storage, and assigns a different second interim storage portion to the second computer for a time duration in lieu of the physical storage upon receipt of an allocation request, during the time duration in which the first interim storage portion is assigned to the first computer, from the second computer requesting allocation of data storage space on the physical storage so that the computers have simultaneous access to the interim storage and the physical storage is free from monopolization by the computers.

Abstract: A caching method for selecting variable size data blocks for replacement or removal from a cache includes determining the size and the unreferenced time interval of each block in the cache. The size of a block is the amount of cache space taken up by the block. The unreferenced time interval of a block is the time that has elapsed since the block was last accessed, and may be determined using a least recently used (LRU) algorithm. The recall probability of each block in the cache is then determined. The recall probability of a block is a function of its unreferenced time interval and possibly size and other auxiliary parameters. The caching method then determines a quality factor (q) for each block. The (q) of a block is a function of its recall probability and size. The caching method concludes with removing from the cache the block with the lowest (q).