Data Placement Scheme on Continuous Media Servers with ZBR Disks

Recent advances in computer technologies have made it feasible to provide multimedia services. As a result, the research and development of continuous media servers has received more attention in recent years. In general, these servers consist of multiple zone-bit recording (ZBR) disks or multiple storage nodes connected through the high-speed network to construct a distributed server. One key issue in developing continuous media servers is the allocation of data into ZBR disks. We propose a novel data placement scheme, called VARBT (variable block-size and data-transfer-time), to fully utilize the characteristics of ZBR disks. The proposed scheme determines data block size in each zone completely according to the capacity of that zone thus the storage utilization is 100%. During the process of data retrieval, the data transfer rate for each block is equal to the bandwidth of each physical zone thus the bandwidth utilization is also maximal. This scheme can be applied not only to a single-disk platform, but also to a multiple-disk server and even a distributed server with multiple storage nodes. Through simulations and performance evaluation, we found that VARBT scheme has the smaller average block size, required memory space and system response time to support more simultaneous streams, and meanwhile it achieves 100% storage utilization and bandwidth utilization.