Fragment reconstruction: providing global cache coherence in a transactional storage system

Cooperative caching is a promising technique to avoid the increasingly formidable disk bottleneck problem in distributed storage systems; it reduces the number of disk accesses by servicing client cache misses from the caches of other clients. However, existing cooperative caching techniques do not provide adequate support for fine grained sharing. We describe a new storage system architecture, split caching, and a new cache coherence protocol, fragment reconstruction, that combine cooperative caching with efficient support for fine grained sharing and transactions. We also present the results of performance studies that show that our scheme introduces little overhead over the basic cooperative caching mechanism and provides better performance when there is fine grained sharing.