Semi-Continuous Transmission for Cluster-Based Video Servers

Recent advances in networking technologies have en-abled high bandwidth communication infrastructures and widespread availability of large bandwidth at clients andservers, making applications such as video-on-demand to the desktop feasible and affordable. Many of the origi-nal continuous media servers assume that clients accessing data from multimedia servers have very limited capability interms of processing and storage. Current trends in storage and processing technology have caused a tremendous dropin storage cost. It is now reasonable to assume that ther

Semi-Continuous Transmission for Cluster-Based Video Servers

With advances in storage technology, the ability to provide client end storage for continuous media applications has become a possibility. Transmission of data in cluster based multimedia environments can be semi-continuous in conjunction with client side buffering and staging. Experiments indicate that a client buffer size (staging degree) of 20 percent (of object size) is near optimal for most objects. The work presented in this paper also addresses the implications of semi-continuous transmission to placement and admission control mechanisms in a cluster-based multimedia server. We improve admission control by introducing a technique called dynamic request migration in clusterbased multimedia servers that is enabled by client staging. Simulation studies demonstrate that close to maximum utilization can be achieved even if at most one migration within the server cluster is performed for each request arrival and each request is migrated at most once during its lifetime. Furthermore, our performance results reveal that with client staging and dynamic request migration, even naive placement techniques are tolerant to extreme variations in request patterns. In fact, our results indicate that under most circumstances one can be oblivious to request pattern variations during placement, eliminating the need to predict relative popularities of objects. 1