Variable Granularity Cache Coherence

L. Mummert and M. Satyanarayanan


Weak connectivity is characterized by slow or intermittent networks. Distributed file systems using weak connections must function in spite of limited bandwidth and frequent connectivity changes. Callback-based cache coherence schemes were designed to minimize client-server communication, but with an underlying assumption that the network is fast and reliable (i.e., a LAN). This paper presents large granularity callbacks as a way to reduce the client-server communication necessary to maintain file cache coherence. Large granularity callbacks trade off precision of invalidation for speed of validation after connectivity changes.