Multimedia Caching Strategies for Heterogeneous Application and Server Environments

In a multimedia system, storage and bandwidth are critical resources since any presentation requires a large volume of data to be delivered in real-time. Caching of multimedia documents in local storage can alleviate large retrieval bandwidth requirements. An important requirement for a multimedia caching policy is to guarantee continuous delivery even when a stream is served from cache. It should also cope with dynamic changes in workload and heterogeneity arising from large and small multimedia files. The proposed Generalized Interval Caching (GIC) policy, that caches intervals between successive streams of a large file as well as entire small files, satisfies all the above criteria. A caching policy needs to cope with additional challenges in a large scale distributed multimedia environment consisting of many heterogeneous servers. The issues include a) routing of requests to ensure good cache hits in each server, and b) balancing of loads across servers. For routing of requests, we introduce the notion of an asset group and propose an affinity routing policy based on this concept. Finally, we adapt the GIC policy for load balancing across servers.