MANAGING READ-ONLY DATA ON ARBITRARY NETWORKS WITH FULLY DISTRIBUTED CACHING

In a large information system, the amount of cache space available to store read-only replicas of data may be limited. Since acquiring these data from their sources may be an expensive and time-consuming operation, it is essential to make efficient use of the available cache space. This cache space may be unevenly distributed over a large number of loosely coupled sites. An intelligent caching strategy is needed to insure that replicas are created often enough that they can be inexpensively reached when necessary, but not so often that important data are forced out to make room. We present such a strategy, which we have developed for use in ALIBI, a networked resource discovery and information retrieval system. The TCF Strategy, as it is called, allows individual sites to adjust their level of cache turnover to provide better overall performance. This novel approach could no doubt be beneficially applied in other distributed systems which use caching. We include discussion and simulation results supporting the efficiency of the TCF Strategy.